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About this blog

Moto Mind is a technical blog written by Paul Olesen who is a powertrain engineer working in the motorcycle industry. The blog covers a wide variety of topics relating to two and four stroke engine performance, design, and optimization.

Entries in this blog

 

Filling Up At The Pump

How Residual Pump Fuel Affects Your Fill Up
This week I have a quick tip I want to share with you regarding buying fuel and filling up gas cans for your bikes. I know many of you, myself included, rely on premium grade gasoline dispensed from local gas station pumps to put endless grins on your faces. One of the downfalls of gas station pumps is that fuel from the previous sale is left in the hose. According to the American Petroleum Institute, the amount of fuel left in a gas pump's hose is around 1/3 of a gallon.   Generally speaking, when two fuels are blended the octane rating of the resulting fuel is approximately the average of the two fuels. So if you had a gallon of 87 octane and a gallon of 93 the resulting blend would have an octane rating of 90. I'll be the first to admit that 1/3 of a gallon of fuel added to a two gallon gas can won't have much effect on the octane rating. For those of you that like numbers, 0.33 of a gallon of 87 added to 1.67 gallons of 93 will yield the following octane rating:   0.33 gallon of 87 / 2 gallons = 16.5% of the total mixture
1.67 gallons of 93 /2 gallons = 83.5% of the total mixture   (0.165 x 87) + (0.835 x 93) = 92 octane blended fuel   So in a two gallon can, the octane rating of the fuel has dropped a point due to the 1/3 gallon of 87 in the pump hose. Unless you have a very well developed performance engine, this isn't anything to lose sleep over. I think a bigger reasons to want to keep that 1/3 of a gallon out of your can is due to the possibility of ethanol being in the hose from the previous sale. Many articles can be found outlining why ethanol should be avoided, but the main reasons include part corrosion due to the exposure to alcohol, rubber seals and o-rings may not be compatible with ethanol resulting in swelling and failure, and some plastics deteriorate when exposed to ethanol. Not to mention ethanol contains less energy than gasoline. Again, we're not talking about a large percentage of ethanol in the overall scheme of things but I prefer to stay away from the stuff when I can.   Fueling Tip
I'm very careful about what I run through my powersport engines. To safeguard against filling up a fuel can with residual fuel from the previous sale, I like to donate the first gallon of "premium" to my vehicle before filling my gas cans. This ensures whatever fuel was in the hose and pump is flushed out and that I'm filling up my cans with premium. If you are borderline OCD about what goes in your engines like I am, you may consider adopting this practice.   I suspect many of you have other tips and tricks regarding fueling. Leave a comment below and share your thoughts and experiences so other motorheads can benefit!   Book News
I also wanted to invite you to check out my book on how to build four-stroke engines, which is now officially available in print form. It took a ton of work to bring the print book together and get the right help on board. The project hasn't been easy, but I'm proud to offer this book to you and can assure you it will make a great addition to your workshop. You can learn more about the book by following this link: The Four Stroke Handbook   To celebrate the arrival of the print book, I'm running a sale until the 27th of September offering all versions of the book at a 20% discount. After the 27th the sale will end and the price will go up. If you've got a build coming up now or in the future and are interested in the book, now is a great time to pick up a copy.   Thanks for reading and have a great week!
-Paul  

Paul Olesen

Paul Olesen

 

Getting Started Servicing Shocks

Hey everyone, this week we're going to switch it up and talk shock absorbers! Over the last few months I've gotten many requests to broaden the topic spectrum and cover other dirt bike topics. So today, we'll do just that by discussing and providing some resources to get you familiar with servicing shocks.   I suspect many of you currently take your shock to someone to have it serviced when it needs to be freshened up. I also bet that it is usually a pain to be without a bike for perhaps a week and that it probably costs around $100 each time? I know I always dreaded having suspension work done on my bike because it seemed to take forever, plus I always had to drive over an hour and half to the nearest shop. For me, those days are long gone. Now do all my suspension work myself.   I believe the majority of you are completely capable of servicing your shocks yourself, but just don't quite have all the pieces of the puzzle you need. Maybe you're not quite sure what tools you need; or once you get the shock apart, you don't know what parts you will have to replace? To help clarify what's needed to service a shock and answer some of the common questions about shock building, I created a detailed guide for you. The guide will help you decide if outsourcing your shock maintenance is the way to go or if you are in fact ready to take the job on yourself.   Before I discuss the details of the guide, I want to provide you with a little background on shock absorbers. For major motorcycle brands, shocks are sourced from the following companies: Showa, KYB, and Works Performance (WP). These three brands are primarily the companies responsible for equipping OEM bikes. Companies, such as Ohlins, cater more towards the aftermarket. Out of the three common OEM shock brand options, Showa and KYB are the go-to's for the Japanese manufacturers, while European brands, such as KTM, gravitate toward the WP brand. So if there is any question as to what brand of shock you have, you can keep this in mind. Out of the three common OEM brands, Showa and KYB shocks are very similar, while WPs feature a slightly different design.   The guide I created is geared towards those of you with either Showa or KYB shocks. Those of you with WP shocks may still find the guide useful, but there are a couple tools missing. Within the eight page guide, you'll be provided information on all the tools you need to service a Showa or KYB shock. These tools include any specialty tools and discuss shock pressurization options. Plus there are some pointers on how to make your own specialty tools if you are on a budget.   Once you get through the tools section you'll be presented with a detailed outline on replacement parts. Knowing what to replace within the shock when it is due for servicing is extremely important and the replacement parts section will walk you right through what you may need. It will also provide you with different options for buying replacement parts.   To receive the eight page guide and learn more about shock servicing, click the following link: Shock Building Tools and Replacement Parts Guide     Thanks for reading and feel free to comment below with any questions or concerns. Bringing high quality DIY advice is what Moto Mind is all about, and I enjoy hearing from all of you and your DIY experiences.   -Paul Olesen
DIY Moto Fix

Paul Olesen

Paul Olesen

 

Leak Down Testing // Pt 2

Hey everybody, hope you are having a great summer thus far! I've been able to get on the bike a lot this summer and I hope you've been getting your fair share of riding in too. A couple weeks ago I covered what a leak down test is, in this blog post here, and how it can be used to determine engine problems. Today I’ll go through and detail how to do a leak down test on your dirt bike engine step-by-step. Now that we're past the halfway point of the summer riding season it may not be a bad idea to check in and see how your engine is doing by performing a leak down test.   How to Perform a Leak Down Test   To perform a leak down test you will need an air source capable of at least 115psi output pressure. Most leak down tests are performed at a regulated pressure of 100psi. This makes testing simple and the correlation of leakage a breeze since you’re working on a scale from 0-100. Lower test pressures such as 90psi can be used in the event that the air system isn’t capable of anything over 100psi or the specific leak down tester you have doesn’t work on a 100psi scale. Just remember if you test at a value other than 100psi, you will need to mathematically determine the leakage percentage since it is no longer a direct correlation.   Leakage testing can be tricky when working by yourself, so if you’re able to round up a friend to help you out it makes things a lot easier. With 100psi of pressure being applied to the piston it is a full time job making sure the piston and crankshaft don’t move. Even with a long breaker bar, holding the crank in place can be quite a task, couple that with having to operate the pressure regulator and obtain a good reading. Again, I highly recommend having two sets of hands on deck for this procedure.   How To Calibrate Your Leak Down Tester   A leak down tester consists of an air inlet, a pressure regulator, two pressure gauges, and an air outlet which pressurizes the cylinder. It is important to check to see if both pressure gauges read the same prior to any testing. If they do this is great, however occasionally the gauges won’t read exactly the same so a baseline will need to be established.   1. Start by setting your air source so that its output pressure is 115 psi. By setting the air source higher than the test pressure this will ensure it does not interfere with the pressure regulation during the test.     2. Slowly increase the leak down tester pressure by adjusting the regulator. Set the incoming air pressure to 100psi.   3. Once the incoming air pressure is set at 100psi read the outlet pressure gauge. If the outlet gauge reads 100psi you are good to go. If the outlet gauge is adjustable set the gauge so it also reads 100psi. If the outlet gauge is non-adjustable (most common) write down the outlet gauge pressure reading. Here you can see the outlet gauge reads 97psi. Since no pressure is being lost between gauges the only explanation for the difference in reading is gauge deviation. The 97psi value will be equivalent to 100psi.     4. After you have recorded the outlet gauge pressure that corresponds to the inlet gauge pressure you are ready to start leakage testing. Set the initial regulated pressure back to 0psi so that the tester doesn’t rapidly and unexpectedly pressurize the cylinder when you reconnect the air line for the test.   Leak Down Test Steps
1. Make sure the petcock is turned off and remove the fuel line from the carburetor or throttle body. Use a rag to catch any fuel draining from the line.   2. Remove the seat and fuel tank from the bike.   3 . Remove the radiator cap and pull out the crankcase breather tube.     4. Remove the spark plug cap . Prior to removing the plug blow compressed air into the plug cavity to rid it of dust and debris so that it can’t get into the engine. Then remove the spark plug.     5. Remove the crankshaft hole cap cover so that you can gain access to the crankshaft.     6. If working from the clutch side of the engine, rotate the engine over so that the piston is just shy of TDC (approximately the width of a punch mark off) on the compression stroke. There are usually alignment marks which can be used depending on the manufacturer to help gauge how close to TDC you are. On the Honda pictured there are punch marks on the crank and balances shaft gears denoting TDC. As you rotate through to just shy of TDC feel for compression building up in the cylinder. As you turn your wrench, resistance should build up as you approach TDC. If you do not feel resistance, rotate the engine over once more and realign to just shy of the TDC markings. This will take you from the exhaust stroke to the compression stroke where you should feel the compression start to build.     If working from the flywheel side of the engine, rotate the engine over so that the piston passes TDC by around a ¼ of a rotation of the crankshaft. Reverse direction and set the crank so that it is just past TDC using the applicable alignment marks. On the Kawasaki pictured you can see the alignment slots. As you came up on the compression stroke you should have felt a little bit of compression build up. If you do not feel resistance, rotate the engine over once more and realign to just shy of the TDC markings. This will take you from the exhaust stroke to the compression stroke where you should feel the compression start to build.     7. Install the leak down tester in the spark plug hole with the regulated pressure set at 0psi initially.       8. It usually takes a breaker bar and two hands to lock the crankshaft from moving once the cylinder is pressurized. This is where having an extra set of hands helps immensely. One person should focus on keeping the crankshaft in position while the other operates the leak down tester. Remember to set the piston just shy of TDC (whichever side is applicable for your application) and to lock the crankshaft in place while the piston is still traveling upwards so the rings sit in the bottom of the ring grooves.     9. Once the crankshaft is locked in place pressurize the cylinder. Slowly turn the pressure regulator up to 100psi.     10. Note the reading of the outlet pressure gauge. This corresponds to the amount of air the combustion chamber is retaining. If both pressure gauges read 100psi when they were calibrated the difference in pressure on the outlet gauge is the cylinder leakage. For example if the outlet gauge reads 95psi the cylinder leakage would be 5%.   If however during calibration both gauges did not read 100psi then the leakage will need to be calculated. For example if the outlet pressure gauge read 97psi during calibration and 92psi when the combustion chamber was pressurized, then the leakage could be found by dividing 92 by 97.   92 ÷ 97 = 0.948   0.948 x 100 = 94.8%
100 - 94.8 = 5.2% leakage   11. Open the throttle and listen for an audible hissing sound coming from the intake, exhaust, or crankcase breather. Also look in the radiator for air bubbles.   Here are the four problems that can result:   1. Air passing through the intake indicates leaking intake valves.
2. Air passing through the exhaust indicates leaking exhaust valves.
3. Air passing through the crankcase breather indicates worn rings.
4. Air bubbles forming in the radiator indicates a leaking head gasket.   12. Depressurize the combustion chamber by turning the regulator back so it is at 0psi and no air is entering the combustion chamber. Unhook the air source and disconnect the leak down tester.   13. Reinstall the spark plug and plug cap.   14. Reinstall the radiator cap and crankshaft hole cap.   15. Reinstall the fuel tank and seat.   That's all there is too it! I hope you have enjoyed my posts detailing how to perform a leak down test. With a little practice you will quickly be able to determine what is going on inside your engine and be better suited to detect major problems before they turn into engine failures. If you have questions, a technique you want to share, or want to leave a comment please do so below.   If you found this post helpful and want more information on how to diagnose engine problems or how to perform high quality engine builds in your own garage, check out my book, The Four Stroke Dirt Bike Engine Building Handbook. You can pick up the eBook immediately and the print book will be out soon!   Thanks for reading everyone!   Paul
DIY Moto Fix - Empowering and educating riders

Paul Olesen

Paul Olesen

 

Save The Salt

I want to switch gears with this post and bring your attention to an issue that is near and dear to myself and many land speed racers. Over the past decade salt mining has caused track conditions at the Bonneville Salt Flats to become worse and worse. Years ago, the salt layer was up to 5 feet thick, today it is less than an inch in some places. Salt mining is partly to blame for the depletion of salt at Bonneville and holding racing events there is becoming extremely hard!   I know not many of you here on TT may participate at, or have ties to Bonneville, but this is great opportunity to band together as powersport enthusiasts and help out those that do. Please help your fellow motorheads by signing the following petition which asks for salt mining to stop at Bonneville. I've signed and hope you do too!   Save the Salt Petition   The salt flats at Bonneville are a special place and it would be unfortunate to not preserve them for future generations. Thanks everyone!   Paul  

Paul Olesen

Paul Olesen

 

Leak Down Testing // Pt I

Determining how healthy an engine is can be tricky business. I’ve previously covered compression testing (here and here), but now I want to discuss what a leak down test is and how to perform one on a four-stroke dirt bike engine. This will be a two part series, with the first part emphasising the details of a leakdown test, and the second part explaining in detail how to correctly perform a leak down test. Let’s get started! Leak down testing is a more definitive way to assess the health of an engine compared to compression testing because a leak down test allows the mechanic to pinpoint the problematic area within the engine. Whether the valves are no longer sealing, the rings are worn, or the head gasket is leaking - a leak down test can be used to find and diagnose all these potential issues.   The way a leak down test works is fairly simple. With the piston just shy of TDC and the valves closed (compression stroke), air pressurizes the cylinder to a defined pressure which is recorded by a pressure gauge. A second pressure gauge is used to monitor the amount of air escaping the combustion chamber. A comparison is made between the air going into the cylinder and the air escaping. The percentage of air escaping is used to determine the overall health of the engine.   The amount of air escaping can roughly be quantified to assess the condition of the engine. When race engines are built, the accuracy and precision that goes into the build results in the lowest leakage values. Most race engines will have a pressure loss of between 0% and 5%. Standard builds resulting in good running engines typically lose up to 15%. Any engine that is close to or past being ready for service will leak from 16% to 30%. These engines will most likely be running poorly, if at all. Engines beyond 30% leakage more often than not are broken and will not run. The more the engine leaks, the worse the engine’s health. Keep in mind these values are provided as a reference point and each engine can be a little different.     It is possible to pinpoint where leaks are coming from once the cylinder is pressurized. When performing the test, the throttle should be fully opened and the radiator cap should be removed. Air can exit the combustion chamber at four points: past the intake valves, past the exhaust valves, past the rings, or past the head gasket. Each of these four points will exhibit a unique tell-tale sign if air is leaking.   Intake valve leaks can be diagnosed by listening for air escaping out the carburetor or throttle body. Exhaust valve leaks can be found by listening for air escaping out the exhaust system. A leaking head gasket will result in air bubbles showing up at the radiator fill cap neck. Excessive leakage past the piston rings will result in pressurizing the crankcase and the resulting air can be traced out the crankcase or cylinder head breather hose. Air escaping past the rings may also be heard or felt passing through the access hole in the engine side cover, where the wrench has been inserted to position the crankshaft. The location at which the air exits when it leaks past the piston rings will depend if the engine has a separate crankcase cavity or a joint cavity. Usually on engines with a separate cavity, the air will be routed through a one way valve, which then directs the air up into the cylinder head and out the cylinder head breather hose.     I want to address one concern you may have at this point. You have probably heard before that the piston should be at TDC when performing a leak down test. In reality there are a couple issues with this that I am going to cover. First, with the short stroke engines of today, keeping the piston precisely at TDC with 100 psi of pressure pushing down on it is next to impossible. The piston and crank will want to rock to either side of TDC. Controlling which side of TDC the piston rests is important. Depending on which side of the engine is used to lock the crankshaft in place and the direction of rotation of the engine, the nut or bolt used to lock the crank in place may either try to tighten or loosen itself from the air pressure pushing against the piston. Even though these are highly torqued fasteners, the air pressure can still occasionally loosen the nut or bolt. This creates a serious problem, because now you’ve got to figure out how to lock out the crankshaft and retorque the nut or bolt.   The second issue is not so much a problem as it is a minor detail. To best simulate ring sealing conditions the rings should sit in the bottom of the ring grooves. This is how they would sit on a running engine and how the test should be performed. By ensuring the rings always sit in the bottom of their grooves, another level of repeatability is added to the test. Simply make sure when setting piston position that the piston is always traveling up just before you hold it in position. If you are working from the left side on a forward rotating engine, it will be necessary to rotate the piston past TDC then reverse direction so the rings sit in the bottom of their grooves and the flywheel nut will not try to loosen itself from the air pressure.   I hope you enjoyed my write up detailing leak down testing. Stay tuned for my next post where I’ll show you exactly how to perform a leak down test yourself. In my eBook, The Four Stroke Dirt Bike Engine Building Handbook, I cover leak down testing in further detail and invite you to pick up a copy if you want to learn more about how to diagnose engine troubles and build four-stroke engines.   Click Here To Learn More About The 4T Engine Building Handbook   If you have questions or thoughts, as always, I enjoy hearing them! Leave your comments below. Don't forget to follow my blog by clicking the button in the upper right hand corner of this page! Thanks everyone.   -Paul Olesen
DIY Moto Fix - Empowering And Educating Riders From Garage To Trail  

Paul Olesen

Paul Olesen

 

Cam Chain Wear and Replacement Tips

I hope you all are getting out on your bikes a lot this summer and are putting some time on them! This week’s post is dedicated to an engine part that is often overlooked, its importance not totally understood, and its service specs minimal. I’m talking about the timing chain. I want to discuss and share with you some signs that the cam chain is worn out.   Just like the drive chain, timing chains elongate, fatigue, and wear out. Luckily, they are not subject to dirt and mud, are bathed in an oil bath, and their overall environment is much better. Before I get into it, one misconception I want to clear up right away is that the timing chain doesn’t technically stretch. Instead, the pins and rotating elements of the chain wear. When the pins wear they become smaller and their mating holes grow larger leading to increased clearances and chain length.   When an engine is run with a worn timing chain engine performance is compromised and the likelihood of related failures is greatly increased (think chain tensioner). Cam timings that are off several degrees will result in a loss of power and the cam chain tensioner will have quite a job trying to take slack out of the valvetrain. When a timing chain elongates it may not do so in a uniform way and parts of the chain may be tighter or looser than others. While automatic cam chain tensioners have proven to be reliable on the majority of engines, some model years, brands, and individuals have fared better than others. A worn timing chain which adds extra slop and inconsistent chain tension to the valvetrain certainly won’t make the tensioner’s job any easier. So it makes a lot of sense to keep tabs on the condition of the chain itself from time to time.   When I was working on a Kawasaki KX250F engine build I took the time to do some comparisons which illustrate the differences you will see between a new and worn out cam chain. First, with the worn chain installed I checked the cam timing. Then I installed the new chain and rechecked the timing. In the table below you can see the intake cam timing was retarded by 6.625° and the exhaust by 9.50° when compared to the new cam chain timing values. For the average weekend warrior this may not seem like much but in terms of performance engines this is miles off the mark!  
Next I looked at chain elongation. With both the new and old chain lying on the workbench it is easy to see a noticeable difference in chain length. The old chain is around 5mm longer than the new one.     You can also easily see how much more flexible the old chain is in comparison to the new chain as well.     These comparisons are all well and good but when do they become practical? Good question, since most of you won’t be checking the timing or removing the chain to compare it to a new one. Unfortunately, very few service manuals provide specifications or guidance on cam chains apart from the “inspect and replace as necessary” phrase commonly found throughout manuals. You may get lucky and find a pin to pin measurement spec you can use from time to time but it is not the norm. My suggestion is to document the applicable attributes of a new chain the next time you have one before installing it into your engine. This way you’ll have some tangible specs to compare to as the chain wears.   Method 1 - The Pin to Pin Measurement
One of my favorite methods to gauge chain wear is to compare pin to pin measurements of new and old chains. To do this you will need to know the total number of pins on the chain. It is easiest to count the number of pins prior to installing the chain, however, pins could still be counted with the chain installed in the engine by marking one of the links, rotating the engine around, and counting.   Once the total number of pins is known a measurement across a set number of pins is taken with the chain installed. I like to span around 6 - 8 pins between the sprockets on a twin cam engine. Unicam engines are trickier and the number of pins you can measure is usually less. It is important to try and measure across multiple pins because the variation between new and old chain measurements will be more pronounced this way. With the new chain installed I measure 1.846” (46.89mm) across eight pins. This is my benchmark measurement and is what I will compare all future measurements to.     Over time, the chain will wear and it will elongate. To keep tabs on chain wear it is never a bad idea to check the condition of the chain whenever you check valve clearances. In the image below I replaced the new chain with the old and repeated my pin to pin measurement across eight pins. This time I measure 1.860” (47.24mm).     The difference in length between the new and old chain can be seen in the table below.  
A chain length increase across eight pins certainly isn’t earth shattering at first glance but that is only a fraction of the chain. To get a better idea of the total chain length increase and the severity of the problem some math is required. My cam chain totals 114 pins and since I only measured eight pins I will need to divide 8 into 114 to determine my length multiplier.   8 pin segments which fit into a 114 pin chain = 114/8 = 14.25   Once I have determined how many 8 pin segments fit into a 114 pin chain I can multiply this value by the change in length between the two chains to determine the total length the chain has increased.   Total Chain Length Increase (inches) = 0.014" x 14.25 =0.200"
Total Chain Length Increase (mm) = 0.36 x 14.25 =5.13mm   The calculated increase is accurate since this is about the difference in length I saw when I laid the chains side by side and measured them. If you aren’t familiar with what changes in length are acceptable this example can be considered one on the far end of the spectrum. The engine had been seriously neglected and wasn’t in real good shape.   Method 2 - What Does the Chain Tensioner Say?
The second way you can observe chain wear is by comparing cam chain tensioner plunger position throughout the chain’s life. To do this the tensioner is temporarily installed, set, and the engine turned over at least four times to allow the tensioner to self tension. Once the chain tensioner has absorbed the chain slack it is removed and the plunger position is noted. Remember to either install the chain tensioner stopper tool or remove the center bolt and spring, depending on tensioner design, so that the plunger doesn’t extend as the tensioner is removed.   In the image below I marked the plunger position with the new chain installed. As you can see the plunger is hardly extended and the second tooth on the plunger is engaged.     As the chain wears the plunger will have to extend out further and further to take up the slack. When I set the plunger with the old chain installed the ninth tooth was engaged on the plunger. Observations like this can be used to gauge cam chain wear and to determine when the chain should be replaced.     Method 3 - Alignment Marks and Feel   Every engine will have specific marks designed into components to aid in the timing of the engine. These marks can also be used to get an idea of the condition the timing chain is in. When correctly timed all alignment marks should be positioned nearly perfectly. As you can see in the image of the Kawasaki engine the two punch marks on the cam gears are aligned with the machined surface of the cylinder head. Both punch marks are visible and in the correct spot.     As the chain wears the tensioner will absorb slack and the cams will retard. In this image with the old chain installed the exhaust cam punch mark is far too high in relation to the cylinder head machined surface and the intake cam is not even visible. This is a good indication that the chain is worn and should be replaced.     Lastly, a basic feel of the tension of the chain between the cam gears can be performed if the engine is of twin cam design.
Here, with the old chain installed there is roughly 6-8mm of slack when I pull up on the chain.     Pushing down I get around the same 6-8mm of slack.     With the new chain installed I get around 3mm of slack when I pull up.
  Finally, pushing down I also get around 3mm of slack.     I hope this write up gives you a few ideas of how you can gauge cam chain wear and that it makes you consider the condition your chain is currently in. I know these methods require a new chain to obtain quantifiable measurements, however, even if you don’t currently have anything to compare your chain to, this write up can be used to give you an idea of where your chain is at in its life. The examples I have provided are at the two extremes of the spectrum, being brand new and severely worn, and anything you encounter should fall between them. For those of you replacing your chain in the near future be sure to take a couple measurements so you have useful info to go off of down the road!   If you have additional tips and tricks relating to cam chain wear I’m all ears and am sure the TT community would love to hear them. For those of you who want to know even more about your engine and are performing your own maintenance check out my book on engine building by clicking here. The Four Stroke Dirt Bike Engine Building Handbook is full of practical engine building knowledge you can use on your next major or minor overhaul.   -Paul Olesen
DIY Moto Fix - Empowering And Educating Riders From Garage To Trail

Paul Olesen

Paul Olesen

 

How To True A Dirt Bike Wheel Yourself

In my last blog post I covered how to lace up a wheel assembly with new spokes. This week I’ll discuss how to properly true the rim. Truing the rim is actually not too difficult. Once you understand the interaction between the spokes and rim, you will make quick work of the job.   To get started a truing stand of sorts needs to be set up. This doesn’t have to be anything special and I used a bench vice, adjuster block, rear axle, spacers, a series of old bearings and washers, and the axle nut. The reason I went to the trouble of clamping the hub in place was to eliminate any possibility of the hub sliding back and forth on the rim, which would make my truing efforts difficult.     This is by no means the only way to create temporary truing stand and you can use your imagination to come up with alternatives. Temporarily installing the wheel back into the swingarm may work equally well if you don’t have a bench vice.   Next, some sort of gauge will be needed so the amount of runout can be seen. I used a dial indicator attached to a magnetic base, however more simple solutions could easily be fabricated.     It isn’t absolutely necessary to measure runout, especially right away when major adjustments may need to be made. Instead you only need to see how the gap between the end of the pointer and rim changes as the wheel rotates. A coat hanger, piece of welding rod, or even a pencil could all be used to the same effect as the indicator shown.   Axial (side to side) runout will be corrected first. Here you can see there is a noticeable difference in gap size between the rim and pointer through a full revolution of the rim.     The goal is to tweak the tension in the spokes so that the gap between the rim and pointer is even as the rim is rotated.     To do this the gap can either be increased or decreased depending on which spokes are tightened or loosened. To decrease the gap, tighten the spokes originating on the side of the rim where you want the gap to decrease. In the previous photo I’m tightening the right side spokes, and in doing so I am pulling the rim to the right. An ⅛ to ¼ turn of the nipple is enough to induce a change. For the given area of the rim that must be pulled over, evenly tighten at least three of the surrounding spokes on the side being pulled. If the rim needs to shift a lot, loosen the opposite side spokes the same amount you have tightened the pull side spokes. This will help keep even tension on all spokes and help to shift the rim.   The process of tightening and loosening the spokes to pull the rim from side to side can be performed at all the high and low points surrounding the rim. Continue to turn and rotate the rim around until the gap between the rim and pointer evens out. Some areas may require tightening the spokes and pulling the rim one way while other areas may need to be loosened to allow the rim to move back the opposite way. Take your time and make small changes as you go. As I mentioned before, it doesn’t take much to see a significant change in rim location as the spokes are tensioned.   As the rim is fine tuned for side to side runout, the pointer can be moved closer to reduce the gap. Reducing the gap as the rim is trued will make it easier to see smaller differences in runout. To really fine tune things I like to use a dial indicator, setting the contact point up on the outer edge of the rim. Again, this isn’t absolutely necessary and similar accuracy could be achieved with a simple pointer.     Here I’ve snapped photos of the high and low points on the rim. The total runout is the difference between the high and low points. In the left picture the needle is 0.0075” (0.19mm) to the left of my zeroed point. In the righthand picture the needle is 0.008” (0.20mm) to the right of the zero. This gives me a total runout of 0.0155” (0.39mm). Most service manuals suggest a max runout of 0.079” (2mm) so I’m well within spec! Quite frankly I was very pleased to get the rim to 0.0155” since the rim is old and slightly dinged up.
The rim I was working on is centered on the hub. Some rims will be offset and it will be more important to pay attention to the relationship between the edge of the rim and a feature on the hub (usually the brake disc machined surface or the machined surface for the sprocket). Your service manual will provide specs for measurement points and specify how much offset should be present. Setting the offset correctly is important because if the offset is off, the front or rear wheel will not be inline with the other wheel. This can make the bike's handling very interesting! I don’t think a little misalignment is too noticeable on dirt, but it is definitely a problem on asphalt.   A straightedge can be used to measure from the indicated surface, outer edge of the sprocket, or brake disc to the edge of the rim. If measuring off the sprocket or brake disc, you’ll need to subtract the thickness of the sprocket or disc from your measurement.     If the rim is not quite positioned right after all the side to side runout has been corrected, it can be shifted at this time. To pull the rim one way or the other, simply evenly tighten all the spokes on the side you are trying to pull the rim to. The opposite side spokes can also be loosened to help allow the rim to shift over. Once the rim is set where it needs to be, half the battle is over!   Next, the radial runout must be corrected. To do this move the pointer so that it sits past the outer edge of the rim.     The gap between the pointer and outer edge of the rim will be monitored and tweaked to achieve evenness throughout the rotation of the rim.
This time to induce change in runout, all the surrounding spokes in the area will either be tightened or loosened evenly in unison. To increase the gap, as I’m doing in the following photo, all the spokes are tightened which pulls the rim inward, enlarging the gap between the pointer and edge of the rim.     To decrease the gap in a specific area all the spokes in that area can be loosened allowing the rim to expand outward towards the pointer. Just like with side to side runout corrections, the nipples only need to be turned an ⅛ to a ¼ turn to make noticeable changes in the gap.   As long as all spokes in the affected area are tightened or loosened evenly, the side to side runout will not be affected. Slowly rotate the rim and make the necessary tweaks until the gap between the edge of the rim and pointer is close to the same as the rim rotates around. The pointer can be moved closer and closer to refine the roundness of the rim. The surface of my rim was too beat up to take accurate measurements so I simply relied on eyeballing the gap to set its roundness.   Once the rim has been trued both axially and radially, the spokes will still be relatively loose. The spokes will all need to be tightened gradually and evenly so that all the efforts of truing the rim are not wasted. Since the majority of rims are either 32 or 36 spoke rims every 4th spoke around the rim can be tightened. This results in an even 8 or 9 step pattern which is repeated four times to tighten all the spokes. First all the red spokes are tightened, then the greens, yellows, and finally blues. Tighten each spoke ¼ turn at a time.   Alternatively, forum member ballisticexchris, suggested a pattern where every third spoke is tightened. This would allow the tensioning of both sides of the rim within the same revolution of the wheel. I've always had good results with the pattern I've outlined but believe his suggested pattern will work equally well and is another option for you to use.     As the spokes are tightened, not surprisingly, the nipples will become harder and harder to turn. The evenness of the spoke tension can be checked by tapping the end of the wrench against the center of the spoke. The spokes will emit a ringing sound and the pitch will be different for spokes which aren’t the same tightness. Continue to work your way around the rim gradually tightening the nipples until all the spokes are similarly tensioned.   Next, use your hand to squeeze the spokes which are parallel to each other together. Squeeze all the spokes evenly around the rim. Squeezing the spokes will help gauge the tension, ensure the heads are fully seated, and help relieve stress built up in the spokes.     After squeezing the spokes together, check the tension in the spokes one final time. Most spokes should only be tightened up to 6Nm and the rim I was working on called for 2.2Nm of torque. A spoke torque wrench is the appropriate tool to use to set the final torque of all the spokes, however I didn’t have one on hand and some of you may not either. Instead I based the final spoke tension on how the new spokes felt in relation to a previously laced rim. This method worked okay, but it is always best to use the right tool for the job.   After you’ve finished tightening all the spokes it is never a bad idea to check runout both axially and radially one final time to confirm the rim hasn’t shifted. As long as the spokes were tightened evenly, changes in runout should not be an issue. Once you have checked runout one last time you are all set to install a new rim strip and put on the tire.     I hope you enjoyed this two part series on building and truing rims. Now that you have the info to feel confident building your own wheels from here on out, and are able to save some cash in doing so, go for it!   Just a heads up, you've got only three more days to use the thumpertalk2015 discount code on The Four Stroke Dirt Bike Engine Building Handbook (eBook) and get 20% off. If you love working on your engine and bringing your four stroke to its highest state of tune, then you are going to love the in-depth precision engine building knowledge I am providing for at-home mechanics and experts in this fully illustrated eBook. The eBook comes in PDF format, is sent immediately to your email inbox, where you can read it or print it off, and bring it into your workshop. To grab your copy and use the thumpertalk2015 discount code before it expires, click here.   If you have tips and tricks pertaining to wheel building, I’d enjoy hearing them. Please leave a comment below!   -Paul Olesen
DIY Moto Fix - Empowering And Educating Riders From Garage To Trail

Paul Olesen

Paul Olesen

 

How To Properly Replace And Install Spokes On A Dirt Bike Wheel

How many of you become disheartened when spokes break, bend, or a rim becomes permanently damaged necessitating a rebuild of the wheel? I know a lot of people think rim building is a black art and are willing to shell out serious dough to avoid the job altogether. This week I want to debunk the black art of wheel building and provide you with an overview of the process, allowing you to take on your next wheel build yourself. Next week, I’ll cover the second half of the project by showing you how to true the wheel.   As you can see I have a great example of a wheel assembly that is way past its prime. The spokes are bent, loose, and the nipples are mostly all stuck. On top of that, the rim is cracked in a couple spots necessitating further repairs.     Before getting started disassembling the wheel, measure the distance from the rim to the ground. When the wheel is built the rim will need to be blocked up at approximately this height. Blocking the rim up will make the wheel much easier to assemble.     The spokes will be offset from one another. Often times this offset necessitates the use of different length spokes. The spoke kit I received came with two different length spokes and there was no indication of which went where. If there are no instructions provided with your spoke kit and your wheel features spokes of different lengths you will need to determine the correct layout of the spokes. This can easily be done by removing two of the old spokes, measuring them, noting their lengths, and positions.     Once you have determined the spoke length you can go to town cutting the rest of the spokes out of the rim using a cutting wheel or other suitable tool.     Remove all the old spokes, then closely inspect the rim for damage. On my rim I had two nice size cracks I had to deal with.     Once the rim has been replaced or repaired, preparations for lacing can begin. Since the wheel will be exposed to dirt, mud, water, and whatever else nature throws at it, I like to coat all my spokes with anti-seize before assembly. The anti-seize will provide a little extra protection against corrosion and help keep the spokes turning freely for a long time.  
  Separate the spokes according to their lengths so that there is no confusion during assembly.     Next, center the hub and block up the rim. Refer back to the measurement you took to establish the correct block height. As long as the rim is not offset to one side or the other it will not make a difference whether you start with the sprocket or brake side.     The outside spokes will be laced first. If you try the inside route you will quickly find that maneuvering the outside spokes into position won’t be possible. Simply install a spoke into its corresponding hole in the hub then align the spoke with its corresponding hole in the rim. The rim may require some rotating to align the spoke with the correct hole in the rim, however it will be glaringly obvious where the spoke must go since the holes in the rim are all angled.     As the spokes are installed, thread on nipples to retain the spokes. Only engage a few threads as you install the nipples. Keeping the rim loose will allow all the spokes to be installed easier as you go.   Once all the outside spokes have been laced in one side, lace all the inside spokes on that side. Don’t be afraid to pull the rim a little bit from side to side to help generate enough clearance so that the end of the spoke can easily pass through the hole in the rim. The rim may also have to be moved up and down a little bit to help center the spoke.     Next, flip the wheel over and begin lacing all the outside spokes on the remaining side. Pulling the rim from side to side and up and down will be necessary to get all the spokes aligned with their respective holes. By the time you are finished lacing you should have a nice fresh wheel assembly.     A good way to check to make sure the spokes have been installed correctly is to compare the thread engagement on each spoke. With all the nipples tightened only a few turns the remaining threads showing on the spokes should be about the same. If the remaining thread length is vastly different between the inner and outer spokes there is a good chance the spokes have been installed incorrectly. If this is the case, the longer spokes will need to go where the shorter ones currently reside to even things out. If this isn’t done, there is a good chance some of the spokes will run out of threads when the spokes are tightened.     After the wheel has been laced, the nipples on all the spokes will need to be tightened. Tightening of the nipples should be done evenly and gradually. An even pattern can be used to tighten the spokes so that the rim does not become offset radially in one direction. Most wheels either feature 32 or 36 spokes. Every 4th spoke can be tensioned to create an even 8 or 9 step tightening pattern. Once this pattern is completed, the next spoke in the sequence can be tightened and the whole process repeated until you have worked through all the spokes. In the picture below all the red arrowed spokes are tightened first, followed by the greens, then the yellows, and finally the blues.     As the nipples are tightened, checking for evenness among the remaining threads is a nice way to gauge symmetry. You may find that there are small differences between the inner and outer spokes in relation to the remaining threads left on them. Instead of comparing the inner and outer spoke threads to one another, only compare similar length spokes as you work. The more care you take to ensure the spokes are tensioned evenly now, the less work it will be to true the rim later on.     Check to make sure that the heads of the spokes fully seat in their holes in the hub. Some heads may get hung up and will require a tap with a punch and hammer to seat them. Relying on the nipple to pull the head into position doesn’t always work well.     Another sign that the job has been done properly is that the spokes will not pass through the ends of the nipples.     At this point you should have a rim that feels tight, is tensioned evenly, and is ready for truing. Check back next week for a write up on the truing process!   If you found this post beneficial and enjoy tackling projects yourself, you may find my eBook, The Four Stroke Dirt Bike Engine Building Handbook a great read. The book is packed full of in-depth precision engine building knowledge, a detailed overview of performance part selection, and many photographic examples which outline what to look for in problematic parts during a build. The eBook comes in PDF format, is sent immediately to your email inbox, where you can read it or print it off and bring it into your workshop. Right now we have an awesome deal running where all website visitors get 20% off when they enter the discount code thumpertalk2015 before purchasing. To learn more about the book, check out the Table of Contents, and read some testimonials, click here.   Do you have any helpful tips you want to add? Please leave a comment below and share your experiences!

Paul Olesen

Paul Olesen

 

How To Repair Your Clutch Basket Dampers For Less Than $30

How to repair your clutch basket dampers for less than $30? Most modern clutches incorporate rubber dampers which help reduce torque fluctuations through an engine’s drivetrain. Single cylinder engines (four-strokes especially) have high peak torque fluctuations since they only fire once every fourth stroke. The dampers situated between the clutch driven gear and clutch basket help smooth out the delivery of power to the gearbox and rear wheel.   The rubber dampers wear out from normal use and in most cases can be replaced. Replacement of the dampers is a fraction of the cost of buying a new clutch basket, does not require a lot of special tools, and you aren’t out anything if the project doesn’t go as planned.   Before I get into the details of replacing the dampers, you are probably wondering how you can tell the dampers are worn out. When the engine is running some additional gear noise coming from the clutch may be noted, but honestly this is a problem difficult to diagnose when the engine is together. Finding this problem is much more likely when servicing the clutch pack or performing other work on the engine.   The easiest way to determine if the dampers have worn is by trying to rotate the clutch gear independently from the clutch basket. Depending on how worn the dampers are this may take a little bit of force, so it is best to lock out the clutch gear and primary drive gear. Once locked, the basket can be rotated back and forth to check for free play. Alternatively the clutch gear can be clamped in the soft jaws of a vice while trying to rotate the basket back and forth. The clutch basket should not move independently from the clutch gear.   In the first photo note the alignment marks are perfectly aligned. In the second photo the marks have shifted about an ⅛” (3mm). This may not look like much, but it will feel like a lot when you twist the basket.     In order to replace the worn dampers the clutch gear will have to be removed from the clutch basket. Rivets are used to secure the gear to the basket and the rivets will have to be drilled out in order to remove the backing plate, gear, and dampers. Once the rivets have been removed, the old holes can be tapped and bolts installed to secure the gear to the basket.   Prior to starting this project you’ll want to make sure you can source new dampers for the clutch basket. Aftermarket clutch manufacturers often offer replacement dampers for their clutches which can work equally well in a stock basket. Hinson, Wiseco, and others supply “cushion kits” which can be purchased from their respective websites, through Ebay, Amazon, or anywhere else you may like to do your motorsport shopping.   Before attempting to dismantle the clutch basket, check to see how much clearance is between the rivets and other features on the engine. Usually the idler gear will be the closest in proximity to the rivets. If the engine has an oil pump gear driven off the clutch, the oil pump gear may also be close to the rivets. Make a mental note of the clearance for future reference. The clearance between the parts when using bolts should be roughly equal to the clearance between the parts when the original rivets were used.     How successful you are at removing the old rivets will in large part dictate the size of the new bolts required. I made a couple of mistakes when repairing my clutch basket, so I ended up using bolts larger in size than I intended. The first mistake I made was a very silly one in hindsight. I didn’t realize that on this particular clutch the rivets are countersunk. Anytime countersunk rivets are used, grinding their heads off won’t work.     Instead of grinding, the rivets should be drilled from the back side. Use a center punch to help get the drill bit started on the right track.     Start with a small bit to create a pilot hole. Once the pilot has been created estimate the diameter of the rivets and select the corresponding bit size.     The diameter of the rivet can be deceptive since both ends have been mushroomed. Most rivets will either be 5 or 6mm in diameter. Err on the safe side and start with a 5mm (#9 bit) before moving up in size. This way if everything is done correctly a 6mm x 1.00 tap can be used to thread the holes. I made the mistake of thinking I was dealing with 6mm rivets so I drilled my holes larger than necessary leaving me with no option but to use an 8mm x 1.25 tap and large 8mm bolts.     Once all the rivets have been drilled, the backing plate can be removed and the rubber dampers will expose themselves. At this point it should be easy to see how the dampers have deformed and no longer fill in the holes properly. The dampers can be directional so take note of the orientation of the dampers at this time.     The dampers may also show signs of cracking and other damage.     Next, you’ll want to determine what bolts to use to secure the gear and backing plate back onto the clutch when it comes time to reassemble the clutch basket. Bolt size will strictly depend on the hole size you drilled to in order to remove the rivets. Ideally, the bolts will only be slightly larger than the original rivet, as this will allow for the easiest clearance between the bolt head and the idler gear. Keep in mind the following tap drill sizes for common metric bolt diameters and thread pitches.   6.00mm x 1.00 - #8 drill bit   7.00mm x 1.00 - letter “B” or 15/64” drill bit   8.00mm x 1.25 - letter “H” or 17/64” drill bit   The bolt head type will come down to your given clearance requirements between the backing plate and idler gear. You may find that a countersunk or button style head will work well. A great resource for selecting fasteners is at McMaster-Carr. If you’ve never explored McMaster-Carr you’ll quickly come to find that they sell just about everything under the sun and if you’re not careful you may part with more money than you originally intended! A few other good sources for metric hardware include Ebay (simply type in the bolt type you’re searching for in the search to turn up lots of results), Maryland Metric, and Boltnet.   For my basket I chose an 8mm x 1.25 Grade 12.9 socket head button which was 14mm long. Once the bolt has been selected, the backing plate and basket can be modified to suit. Start by enlarging the backing plate so that it will accept the bolts.     Once the backing plate has been drilled, if necessary, drill the basket rivet holes to the correct size so that the holes can be tapped. Be very careful when centering the drill bit in the hole. The more precise you are in this step the better the backing plate holes will align. Since the bit may have wandered a little bit when drilling the rivets out, it may be impossible to get everything centered just right. This isn’t the end of the world and adjustments can be made to the backing plate to get it to fit correctly.     Once all the holes have been drilled, carefully tap them using an appropriately sized tap.     After all the holes have been tapped, carefully add a chamfer to the top of the hole. This will deburr the hole and remove any raised edges which may keep the backing plate from sitting flat against the bosses. A drill bit larger in diameter than the hole or a deburring tool can be used to deburr the edge of the hole.     Proceed to fit the backing plate to see how the holes are lining up. As you can see, my holes wandered quite a bit when I drilled them so my backing plate holes don’t align well with the basket holes. I’ve shaded in with blue marker where I need to elongate the hole in order for the bolt to fit. Make sure an alignment mark is added to the backing plate and basket since the hole pattern is no longer symmetrical.     I used a rotary burr to elongate the holes, however, a hand file will work just as well. It will require a little more elbow grease and take a little longer though. Deburr the backing plate to remove any burrs which may keep it from sitting flat against the clutch basket bosses.
After making adjustments to the holes, all the bolts should easily thread into their respective holes.     At this point the clearance between the bolt heads and gears can be checked. As you can see, my bolt heads are too tall and will need to be ground down once they are permanently installed.     Grinding the heads is not ideal, but it ended up being inevitable for my application. Any necessary grinding will take place after final assembly since there may not be enough engagement between the bolt and bit.   After clearances have been checked and everything is ready for final assembly, the parts should all be thoroughly cleaned to remove any metal debris stuck to them. The clutch gear and new dampers can be reinstalled. If the dampers are directional, make sure they are installed in the correct orientation.     Next, install the backing plate. Apply a permanent thread locking agent to the bolts. Then install all the bolts. The diameter of the bolt and grade will dictate how it should be torqued. For your reference with the locking agent applied, I torqued my Grade 12.9 8mm x 1.25 bolts to 30Nm. Follow this link to view guidelines for torque specs on other metric fasteners.     If you were successful in selecting a bolt that clears the gears behind the clutch then you can give yourself a pat on the back as your work is done! If you are using bolts which must have their heads shortened this can be done using a grinding disc, mill, or any other suitable tool. Remove material from the bolt heads slowly and take just enough away so that the head clears the idler gear and any other obstacles.     I ended up removing most of the head and won’t be able to tighten or loosen the bolts, however, I planned for this prior to grinding. Removing the bolts isn’t a great concern because other parts of the basket such as the fingers will wear out sooner than the dampers will.     In total this fix cost me just under $30 and will prolong the life of my clutch basket. With this write up you should also be able to repair clutch baskets with worn dampers, save yourself money, and prolong the life of expensive engine parts.   If you have questions, thoughts, or want to share your experiences - leave a comment below!   Thanks for reading guys and have a great rest of your week.   -Paul Olesen
DIY Moto Fix - Empowering And Educating Riders From Garage To Trail

Paul Olesen

Paul Olesen

 

Cast Your Vote For The Cover Of The 4T Dirt Bike Engine Building Print Book

We just got back the two cover design options for the print book version of The Four Stroke Dirt Bike Engine Building Handbook, and guess what? We are asking for YOUR help in choosing the design. We figured what better way to know what our fellow motorheads are going to like than to put it up to a vote. The two options are pictured below and whichever cover gets the most votes wins.     Cast your vote for Cover #1 or Cover #2 by leaving us a comment below. We are tallying up all the votes over the next five days and will have a winner by the end of the week!   For those who have been wondering when the print version of the book will be ready to order, stay tuned. You aren't too far off from getting a shiny new print engine building handbook sent right to your doorstep.   For those who want to get their hands on the downloadable and printable eBook version, we are still running the 20% deal for the ThumperTalk community. Be sure to use the discount code: thumpertalk2015 to receive 20% off your purchase. Grab your copy by clicking here >> The Four Stroke Dirt Bike Engine Building Handbook (eBook)   Thanks for your support and I appreciate your input on the cover design!   Paul

Paul Olesen

Paul Olesen

 

The Four Stroke Dirt Bike Engine Building Handbook

I hope all of you have been getting out on your bikes and riding as much as possible now that spring is in full effect. For those of you in warmer climates, please don't remind me you have been riding year round without any additional layers, this only makes me jealous and forces me to seriously consider the thought of moving. I've been very busy the past month, but have tried to get a couple hours in on the bike every Saturday. There truly is no better therapy than going out and spanking the bike around after a long week of work! I'm very excited to announce that the eBook I have been working on these last four months, The Four Stroke Dirt Bike Engine Building Handbook, is officially released. I want to spend a little time talking about what the book has to offer you as a dirt bike engine building enthusiast; I don't think you will be disappointed. Below is a snapshot of the table of contents as well as a few interior pages, just to give you an overall look at what this book covers for you. What could this book possibly be about that other reference materials, like service manuals, don't already cover? I wrote The Four Stroke Dirt Bike Engine Building Handbook to be an all encompassing guide on engine building. Whether you are building a stock or performance engine, this book provides a specific framework for you to understand and use throughout the entire process. From the moment there is doubt about the engine's condition to the time the rebuilt engine is broken in, I give you a step-by-step guide to help you work towards a successful build. My aim was to create a definitive resource that hit on all the topics you may question as you proceed through an engine build, and teach you the how and why behind the way things are done. I've been very fortunate to work with talented engineers and builders over the years. This book is a way to share the knowledge I have learned from them with you, a way to bridge that gap for at-home engine builders to enable you to be better equipped with the proper insight and information when it comes time to rebuild. Today's modern four-stroke dirt bike engines are fine pieces of engineering, are designed to exacting tolerances, and require a great deal of care and precision in order to keep them operating at their finest. If you don't work with engines on a regular basis or haven't been taught by a great mentor, there are a lot of subtleties which can be overlooked that I've written extensively about for you. Throughout the book, engineering knowledge and practical experience are fused together to detail the how and why behind the way procedures are performed, parts are designed, and engine performance is affected. This is the most important and valuable aspect of the book, and it's something you won't find in any service manual. The book doesn't just tell you to bolt part A to part B, it teaches and explains the correct way assembly procedures should be performed and why it is necessary to do so. It also explains the intricate relationship between parts. For example, the interaction between the valve guides, seats, and valves must be understood in order to understand why valve seat cutting shouldn't be left to just anyone. Along with the practical building how and why, an entire chapter has been dedicated to detailing how performance parts affect engine performance. Within this chapter helpful suggestions are provided to aid you in choosing the correct components for your build, depending on your specific riding needs. If you don't work directly with engines on a regular basis, it is hard to acquire practical experience when it comes to diagnosing problems and detecting abnormally worn parts. Not knowing what to look for when inspecting engine components can lead to improper diagnosis and assembly of an engine, which could still have bad parts in it. I have filled the book with as many photos and written examples of worn or damaged parts as I could so that you will know exactly what to look for when inspecting engine components as you proceed through the build process. This is invaluable practical knowledge, which only comes with experience, and is not something you will find in your service manual. Now that you have a general feel for what the book is about you may have more questions. One I've been asked a few times now by friends and fans is how can you write a book applicable to all makes and models? Believe it or not, the variations of dirt bike engine designs between manufacturers are in truth very minimal. Sure, there are physical and locational differences. One brand may use two camshafts while another uses a single cam, or one may put an oil pump on the left side of the engine while the other puts it on the right, but the overall layout of the engines and function of the parts are all similar. I did not write this book with the focus being on the little differences between brand X and brand Y. I wrote this book outlining specific techniques and inspection points applicable to every type of engine you will encounter. The function and the way components interact does not change just because they are physically different or located in different places. This is imperative to understand in order to get the most out of the book. To ensure I've covered the various ways parts interact and can be assembled, I've used two different engines throughout the book as examples and have provided specific instruction on how to deal with assembly differences that will be encountered across the Japanese and European brands. If you have a thirst to learn more about how your engine works and a desire to correctly disassemble or assemble an engine to professional standards, you will benefit greatly from this book. Whether a complete beginner or a seasoned builder, with over 300 pages and 250 images worth of information, there is fresh and useful knowledge for everyone. There is also valuable material packed into this handbook that doesn't just pertain to the act of building the engine. I include instruction on diagnosing engine problems, sourcing and determining which parts to replace, using precision measuring tools, setting up your workshop, and additional tests and inspections that should be performed when preparing racing engines. If you just want to build your engine back up to stock spec, you are covered. If you want to go the extra mile and prepare a racing engine, you are also covered. In a way this book allows you to choose your own ending by giving you all the tools and knowledge you need to complete your build at whatever level you decide. The book is available in both print and eBook format. We ship worldwide and offer door to door tracking for overseas shipments. I also created a discount code just for the ThumperTalk community that gives you another 20% off the list price. Be sure to enter the code thumpertalk2015 before purchasing. Order the print book directly from our website or on Amazon. You can order the eBook directly from our website and it will immediately be sent to your email inbox. From there you can download it to your electronic device of choice to read or print. You also have the option to just view it online.  This is one tool you can add to your toolbox that won't wear out and break on you and can be used universally. Thank you for your support of DIY Moto Fix these last few months, and enjoy the heck out of the book! Thanks for reading guys and have a great week. -Paul Olesen DIY Moto Fix - Empowering And Educating Riders From Garage To Trail

Paul Olesen

Paul Olesen

 

Precision Measuring For The At-Home Mechanic // Part 3

As we wrap up our final post on precision measuring for the at-home mechanic, I hope you have found this three part series on measuring helpful and informative. If you need a brush up or haven't gotten a chance to read Part 1 or Part 2, we compiled all three parts into a free guide for you. You can download your free copy by clicking here. This three part series comes right out of the book I published, The Four Stroke Dirt Bike Engine Building Handbook. I think you're going to love the in-depth knowledge and information provided in this book on four stroke dirt bike engine building. To learn more and order your copy click here. In this post I will be covering the final six precision measurement tools you have at your disposal. Each measurement tool in this post features a description of appropriate applications for the tool and a step-by-step tutorial on how to use it. This post is designed as a reference so that you can easily come back to it at any time as you become more comfortable using measurement tools during a rebuild. PLASTIGAUGE Plastigauge is one of the only measurement tools you won’t mind throwing away once you are done using it. Plastigauge is a measurement tool used to check the clearance between parts. The plastigauge consists of little strips of plastic which are inserted between two parts. Once assembled the plastic strip is compressed. The amount the strip compresses can be measured and correlated to a chart (supplied with the plastigauge) which defines the clearance for the measured compressed width of the strip. For engine building purposes plastigauge is ideal for checking clearances between engine components utilizing plain bearings. The plastigauge is a great tool for confirming clearance and measurements. Another plus is that unlike most other measuring tools, plastigauge is cheap! Plastigauge is usually sold in an assortment of sizes which cover multiple clearance ranges. Plastigauge strips will come in different diameters and each diameter will be capable of measuring a certain clearance range. Where to Use: Examples include cam to cam journal clearance, crank bearing to crankshaft journal clearance, and crank pin to rod bearing clearance. Calibrating Plastigauge Finally a measurement tool where no calibration is necessary. Just make sure you choose the appropriate size strip for your application. Also make sure the plastigauge is fairly new. Plastigauge does get old after awhile and using old plastigauge may not yield accurate results. Reading Plastigauge After the plastigauge has been compressed use a calipers to measure the width of the compressed strip. Record the width in your notebook. Then look at the clearance chart provided with the plastigauge to determine the clearance that corresponds to the measured width. Yes, it really is that simple. How To Use 1. Clean the parts being assembled 2. Insert a small strip of plastigauge between the parts being assembled. 3. Carefully lower the mating part down onto the plastigauge. Take great care to lower the part straight down so the plastigauge doesn’t move. 4. Install the fasteners used to secure the parts together. 5. Tighten the fasteners to the torque value recommended by the manufacturer. Follow any special tightening patterns that may apply 6. Carefully loosen the mated parts. Again, follow any special instructions for loosening provided by the manufacturer. 7. Remove the part. Check to see which part, if any, the plastigauge has stuck to. 8. Use a calipers to carefully measure the width of the plastigauge. 9. Refer to the chart provided with the plastigauge to determine the clearance which corresponds to the measured strip width. Tip: With a keen eye taper and out-of-roundness can also be spotted by using plastigauge. Keep an eye out for variations in strip width after it has been compressed for clues about the condition of the bore. DIAL INDICATOR A dial indicator measures variations in height by utilizing a plunger which travels up and down. As the plunger travels a dial gauge records the amount the plunger has moved. For engine building purposes a dial indicator is a handy tool to have when measuring valve lift and finding top dead center. There are a wide range of dial indicators on the market. Choosing the best one for engine building may be daunting if you’re not familiar with them. There are two main features you want to look for when selecting an indicator. The amount of travel the indicator has and the resolution of the indicator. Choose an indicator with around 1.0” (25mm) of travel which has a resolution of 0.001” (0.025mm). This type of indicator will work well for engine applications. In addition to the indicator getting a few accessories for the indicator will be beneficial. Most indicators are not sold with a base. Magnetic bases are really handy when setting the indicator up and provide a means of securing the indicator so it can’t move. Even when working with aluminum parts (ex. cylinder head) a magnetic base can be utilized by bolting a flat piece of steel to the aluminum part. Dial indicators usually come equipped with rounded contact points which are ideal for measuring flat surfaces. Occasionally you may encounter a setup which requires a different contact point. A variety of contact points are offered for indicators and having an assortment never hurts. Tip extensions are a must have if you plan on doing any deep depth work with the indicator. One situation which routinely requires a tip extension is when using the indicator to find top dead center of the piston. Tip extensions can be bought in multiple lengths. Where to use: Examples include measuring valve lift, and finding top dead center. Reading Dial Indicators Reading a dial indicator is very similar to reading a dial calipers. The only difference is the dial indicator’s gauge face is equipped with a second smaller dial face. For an indicator with a resolution of 0.001” the small face is divided into 10 graduations. Each graduation represents a tenth of an inch. The outer dial face is divided into thousandths of an inch. Each time the outer needle rotates one revolution around, the second small needle tallies a tenth of an inch. This eliminates the need for the user to keep track of how many times the needle has gone around. The total measurement is comprised of the number of tenths of an inch the smaller needle is indicating plus the number of thousandths the large needle is indicating. In the picture above the dial indicator reads _0.136". For metric and other resolutions of dial indicators the reading process is identical to the above. Take note of the units and resolution and proceed to read the indicator accordingly. Calibrating Dial Indicators Checking and adjusting the accuracy of dial indicators usually can’t be done easily in one’s own shop. For dial indicator calibration the indicator would have to be sent to a calibration lab. Fortunately, the applications an indicator is used for when building engines doesn’t require the utmost accuracy so calibration is seldom a problem. How To Use: 1. Clean the contact point of the indicator and the part which will be indicated. 2. Carefully set the indicator up so that it is fixed to a sturdy base which can’t move. 3. The amount of travel in each direction you will need depends on the specific application you are measuring. Consider the motion and travel of the part you want to measure and set the indicator accordingly so that it doesn’t run out of travel halfway through measuring. For example, when measuring valve lift you would want to engage the indicator so that around a quarter of the plungers travel has been used. 4. Square the spindle of the indicator being measured. The more square the indicator spindle is to the part the more accurate the readings will be. If the indicator is set at an angle to the direction of travel of the part the indicator will not read accurately. Keep this in mind and always try to set the indicator spindle as square as possible to the part being measured. 5. Zero the indicator by rotating the gauge face so the outer needle aligns with “0”. For example when measuring valve lift the zero point would be when the valve is fully closed. When checking runout the zero point may be a low or high point. 6. Move the part being indicated a few times returning it to its starting position each time. Check to make sure the indicator consistently reads “0”. If it doesn’t then carefully adjust the gauge face to realign the needle. 7. Once the indicator has been zeroed proceed to move the part being indicated and take measurements. 8. After measuring return the part to its original position. Occasionally an indicator can get bumped or something can happen during the procedure. This is a good way to confirm one last time that the indicator is still zeroed. DIAL TEST INDICATORS Dial test indicators are very similar to dial indicators, however their primary function is more as a comparative tool than a measurement tool. The main difference between a dial indicator and dial test indicator is the dial test indicator uses a contact point which pivots instead of a plunger that travels up and down. This pivoting action results in an arcing path instead of a straight up and down path. The test indicator is best suited for taking comparative measurements and zeroing runout. For engine building purposes this makes a pair of dial test indicators well suited for measuring the runout of a crankshaft. Just like dial indicators, test indicators are made with different lengths of travel and different resolutions. The most suitable resolution for crankshaft truing and inspection purposes is 0.0001” (0.0025mm). Most test indicators with a resolution of 0.0001” will have a travel of 0.008” (0.203mm) or 0.010” (0.254mm) which will be suitable for crankshaft inspection. The test indicators will require fixturing so having a pair of bases, stands, and clamps is necessary. Fortunately, the test indicators use similar mounting systems as dial indicators so if you have fixturing for dial indicators you are all set to mount the test indicators. Where to use: Examples include crankshaft inspecting or truing. Reading Dial Test Indicators The gauge face of a dial test indicator is symmetrical. The face is divided into graduations based on the resolution of the test indicator. Each side of the face represents half of the total travel of the test indicator. Reading the gauge is simply a matter of determining how many graduations the needle has moved from its starting point to its ending point. Calibrating Dial Test Indicators Like dial indicators, calibrating dial test indicators is usually done by a professional calibration lab. As long as the test indicator is well cared for the need for calibration should be infrequent. How To Use: Since the contact point of the test indicator travels in an arc the way the indicator is set up has an impact on measurement. This is the main reason test indicators can’t be relied on heavily for taking measurements and instead are used for comparing. 1. Clean the contact point of the indicator and the part which will be indicated. 2. Carefully set the indicator up so that it is fixed to a sturdy base which cannot move. 3. Most test indicators function best when the contact point is perpendicular to the direction of travel of the work piece. Some indicators differ slightly and should be set at a slight angle, so confirm with the instructions supplied with your test indicator to attain the correct orientation. 4. The majority of test indicators work best when the contact point is preloaded. As a rule of thumb a 1/10 - ¼ revolution of the needle is about right for setting preload. Instructions supplied with individual indicators may have specific preload instructions. 4. Rotate the part to find the high or low point. Zero the indicator by rotating the dial face so the needle aligns with “0”. 5. Move the part being indicated a few times returning it to its starting position each time. Check to make sure the indicator consistently reads “0”. If it doesn’t then carefully adjust the gauge face to realign the needle. 6. Once the indicator has been zeroed proceed to move the part being indicated and take measurements. 7. After measuring return the part to its original position. Occasionally an indicator can get bumped or something can happen during the procedure and this is a good way to confirm one last time that the indicator is still zeroed. TRANSFER GAUGES Transfer gauges are measurement tools which don’t yield a direct measurement. They are simply tools which can be used to transfer the dimensions of something requiring measurement to a measurement tool. There are two types of transfer measurement tools commonly used in engine building, small hole gauges and telescoping gauges. Transfer gauges can be tricky to use accurately for a couple reasons. First, they introduce a second source for error. Instead of taking a direct measurement the measured part must first be sized using a transfer gauge. Then the gauge must be measured by a measurement tool such as a micrometer. It is easy to see how mistakes can accrue in this situation. Second, transfer gauges rely heavily on feel to obtain accurate measurements. If the user of the gauge is unskilled, the transfer measurements could be all over the board. Taking these points into consideration transfer gauges can still be incredibly helpful when measuring engine parts. Transfer gauges are one of the most relied on methods of accurately measuring internal diameters. SMALL HOLE GAUGES Small hole gauges are used to transfer internal measurements usually less than ½” in diameter. A small hole gauge has a split in its head which allows the head to expand or contract to the size of the part being measured. An adjustment knob at the end of the handle is turned to expand or contract the head. The head on the gauge can either be a full or half sphere design. The half sphere designs have the advantage of being able to measure blind holes. Small hole gauges are usually sold in sets capable of measuring from around 0.125 - 0.500” (3.175 - 12.4mm). Each set is comprised of around four gauges with each gauge being able to measure a certain portion of the set’s total range. For engine building purposes, small hole gauges are primarily used to measure the inner diameters of valve guides. Where to use: Valve guides How to use: 1. Clean the bore of the part to be measured and the head of the small hole gauge. 2. Slowly turn the adjustment knob on the gauge expanding the head of the gauge inside the bore of the part being measured. 3. Simultaneously, gently rock the gauge back and forth and fore and aft inside the bore until the head of the gauge just starts to drag on the bore of the part. As you rock back and forth make sure the handle of the gauge passes through the point where the handle is square to the bore. 4. Remove the gauge. 5.Use a micrometer to measure the diameter of the gauge to determine the diameter of the part’s bore. Since the gauge can easily be compressed little to no pressure can be applied by the measuring faces of the micrometer. 6. Slide the gauge back and forth and fore and aft as you delicately tighten the ratchet or thimble of the micrometer. An accurate reading will be obtained when the micrometer just starts to drag against the gauge. Remember to measure perpendicular to the split in the gauge. 7. Lock the the spindle of the micrometer and read the micrometer to obtain the bore diameter. Hot Tip: Since this is partly an exercise of feel, take multiple measurements until the measurements start to yield the same results. This way you can be certain the measurements are accurate. TELESCOPING GAUGES Telescoping gauges are the big brothers of the small hole bore gauges. Telescoping gauges are shaped like a “T”. A tightening knob is situated at the handle end and it controls one or two spring loaded plungers (dependent on gauge type). Once the knob is loosened the plunger(s) expand outwards to capture the diameter of the bore being measured. The plunger ends are convex so the gauge can be rocked back forth to obtain the measurement. Telescoping gauges are usually sold in sets capable of measuring from around 0.3125 - 6.0” (8 - 152.4mm). Each set is comprised of around six gauges with each gauge being able to measure a certain portion of the set’s total range. Where to use: Examples include lifter bucket bore and cylinder bore. How to use: 1. Clean the bore of the part to be measured and the ends of the plungers on the telescoping gauge. 2. Set the gauge inside the bore with one plunger touching the side of the bore. 3. Slowly loosen the adjustment knob on the gauge handle expanding the plungers of the gauge inside the bore of the part being measured. http://www.thumpertalk.com/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=231329 4. Set the gauge up so that the handle is just out of square with the bore. 5. Tighten the adjustment knob down. 6. Gently wiggle the gauge back and forth while passing the gauge through the bore. Only pass the gauge through the bore once. This will center the gauge and set the plungers to the diameter of the bore. http://www.thumpertalk.com/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=231330 7. Clean both measuring faces. 8. Use a micrometer to measure the diameter of the gauge to determine the diameter of the part’s bore. Since the gauge can be compressed, little to no pressure can be applied by the measuring faces of the micrometer. 9. Slide the gauge back and forth and fore and aft as you delicately tighten the ratchet or thimble of the micrometer. An accurate reading will be obtained when the micrometer just starts to drag against the gauge. [series of pics showing measurement direction 10. Lock the the spindle of the micrometer and read the micrometer to obtain the bore diameter. Hot Tip: Since this is partly an exercise of feel, take multiple measurements until the measurements start to yield the same results. This way you can be certain the measurements are accurate. V-BLOCKS A V-block is a large precision machined metal block with a V in it. During an engine build V-blocks are used primarily for checking runout of cylindrical parts such as the crankshaft. http://www.thumpertalk.com/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=231331 When shopping for V-blocks a precision ground matched set should be purchased. Fancy versions may come with magnetic bases, multiple Vs, clamps, or rollers. While some of these features are nice they certainly aren’t necessary and add to the cost. That wraps up our three part series on precision measuring for the at-home mechanic, thanks so much for reading! If you would like all this precision measuring information in one place so you can come back and easily reference it, we created a free guide for the ThumperTalk community that you can download right to your computer or phone. Click here and I'll email the The At-Home Mechanic's Guide To Precision Measurement right to you so you can have it organized in one place. If you are interested in owning a copy of The Four Stroke Dirt Bike Engine Handbook, you can learn more by clicking here. Thanks again for reading and feel free to leave a comment below! -Paul Olesen DIY Moto Fix | Empowering And Educating Riders From Garage To Trail.

Paul Olesen

Paul Olesen

 

Precision Measuring For The At-Home Mechanic // Part 1

This week I want to provide you with some in-depth knowledge on the world of precision measurement. As at-home mechanics who want to take their rebuilding skills to the next level, learning about precision measurement and how to properly use precision tools is the final frontier. This post comes right out of The Four Stroke Dirt Bike Engine Building Handbook, the engine building book I am currently writing for my fellow riders who want to bring their engine building skills into a professional realm in their own garage. This post is part one of three that will cover the correct use and implementation of precision measurement tools when rebuilding your own engine. The world of measuring is so complex by nature that one could get wrapped up writing an entire book on the subject and still not cover it all. This is not my intention with my engine rebuilding book. My aim is to provide you with the principles on how measuring works, what the most important takeaways are on the subject of measuring, and an overview of how to use the tools correctly. Once informed you can then delve further into the intricacies of measuring for your own needs. There are three terms that are important to the fundamental understanding of measurement. These terms are often mixed up, confused as meaning the same things, or used incorrectly. These terms are accuracy, precision, and resolution. Understanding these three terms will go a long way in ultimately understanding measuring and the capabilities of measurement tools. ACCURACY Accuracy is how close a given measurement is to the “true” value of an object. For example, if a valve stem was exactly 0.1969” (5.000mm), accuracy would quantify how close the measurement tool was to the true value. PRECISION Precision is a measurement of repeatability. For example if an object was measured five times, precision would quantify how close the five measurements are to one another. Another way to think of precision is the finiteness of which a measurement tool can be read repeatedly and reliably. RESOLUTION Resolution is the smallest distinguishable value of a measurement tool. If a ruler is divided up into tenths of an inch then the resolution of the ruler is one tenth of an inch. A micrometer that can be read to one ten thousandth has a resolution of one ten thousandth of an inch. Just because a measurement tool, such as a micrometer, has a very fine resolution doesn’t mean it will be accurate or precise to that resolution. This will be explained more shortly. Distinguishing the difference between accuracy and precision is most easily done with a set of pictures. Four scenarios can occur when measuring. A measurement can be both accurate and precise.
A measurement can be accurate but not precise.
A measurement can be precise but not accurate.
A measurement can be neither accurate nor precise.
It is imperative when measuring engine parts that the measurements are both accurate and precise as represented in the first picture. Precise and Accurate Accurate but not Precise Precise but not Accurate Neither Precise nor Accurate Now let's see what happens when the bullseye is taken out of the picture: Notice that if the bullseye is taken out of the picture there would be no way to reference if the shots were accurate? It would be easy to tell that the “accurate but not precise” and “neither precise nor accurate” scenarios didn’t yield meaningful results. However, the scenario with “precise but not accurate” results could be misleading for someone measuring. This is exactly why it is important to calibrate measurement tools before using them. By calibrating a measurement tool you ensure it is accurate prior to measuring an unknown object. What Affects Accuracy and Precision? Now that the key parts of accuracy, precision, and resolution have been outlined how do they apply to measuring tools and measuring? I want to go over three factors that lead to variation in accuracy and precision when working with measurement tools. 1. Type of Tool and Tool Quality Different types of measurement tools will have different ranges of accuracy. For example a digital 0-6” calipers is usually accurate to 0.001” (0.025mm), however it will have a resolution of 0.0005” (0.0127mm). Just because the resolution is 0.0005” (0.0127mm) doesn’t mean that is how accurate the tool is. For a 0-1” micrometer the accuracy is 0.0001” (0.0025mm) and so is the resolution. Be sure to keep accuracy and resolution in mind when using and shopping for measurement tools. Decent measurement tools should have the manufacturer’s accuracy specified in the tool description. Using a calipers to measure the bore of a cylinder is a good example of using a measurement tool which is not accurate enough for the task at hand. Most dirt bike cylinder bores have a diametric range in the neighborhood of 0.0006” (0.0152mm), taper limit of around 0.0004” (0.0102mm), and out of round limit of around 0.0004” (0.0102mm). A calipers is off an order of magnitude in accuracy and is not capable of doing the job. 2. Temperature The temperature a measurement is taken at can have a large effect. A standard has been set for the temperature parts are measured and inspected to in the engineering and metrology worlds. That standard temperature is 68°F (20°C), which is what you should strive for when you are precision measuring parts. The reason temperature is important is due to the concept of thermal expansion. In a nutshell thermal expansion explains how an object’s volume will change as temperature changes. As volume changes so does length, which is what matters in this case. Equations for linear expansion will be used to show the role temperature plays on the diameter of a cylinder bore at two extremes: 32°F (0°C) and 100°F (37.78°C). Consider a cylinder that has a bore of 3.7795” (96.000mm) - typical of a 450cc engine. At 68°F we will say the cylinder measures exactly 3.7795” (96.000mm). What happens when the same cylinder is measured at 32°F (0°C) and at 100°F (37.78°C)? Let’s work it out. The formula for linear expansion is: ∆L = α x D x ∆T where: ∆L = Change in diameter of the cylinder bore α = coefficient of thermal expansion for aluminum (13.3 x 10^-6) in/in °F D = original diameter of the cylinder ∆T = Change in temperature (Final Temperature - Initial Temperature) α = (13.3 x 10^-6) in/in °F D = 3.7795” ∆T = 32°F - 68°F = -36°F Now it all gets put into the equation and solved. ∆L = (13.3 x 10^-6) in/in °F x 3.7795” x -36°F = -0.0018” ∆L = -0.0018” (0.046mm) So the 3.7795 inch cylinder has now shrunk to 3.7777 inches (95.954mm). A 36°F (20°C) change in temperature has caused the aluminum cylinder bore to change by 0.0018” (0.046mm)! In terms of cylinder measurements this is a big change and illustrates just how important it is to measure engine components in the right environment. A similar change can be seen when the cylinder is measured at 100°F (37.78°C). α = (13.3 x 10^-6) in/in °F D = 3.7795” ∆T = 100°F - 68°F = 32°F Now it all gets put into the equation and solved. ∆L = (13.3 x 10^-6) in/in °F x 3.7795” x 32°F = 0.0016” ∆L = 0.0016” (0.041mm) So the 3.7795 inch cylinder has now grown to 3.7811 inches (96.041mm) . In conclusion if you work in environments that are at one extreme or another on the temperature spectrum you are guaranteed inaccurate measurements. The scenario where measurements are precise but not accurate would be a good illustration for how temperature affects measuring. 3. User Error Lastly, the person doing the measuring also has an effect on the precision of the measurement. Another example is the most effective way to illustrate my point. Consider a situation where an inexperienced measurer measures a part five times and returns five different measurements. Next, a seasoned measurer measures the same part five times and returns the exact same measurement all five times. Both people measuring used the same measurement tool and carried out the measurements at the same temperature. The only variable that wasn’t the same was the person doing the measuring. This variation of measurement between people measuring isn’t that uncommon and happens all the time. Even two different seasoned professionals who inspect and measure parts daily can end up with different measurements for the same part. It is very likely that the variations in the professionals’ measurements will be much more precise when compared to one another. How do I know my Measurements are Accurate and Precise? Alright we’re starting to get into the more interesting - I mean practical, aspects of measuring. Hopefully the last few sections haven’t bored you or deterred you from wanting to measure your own engine components. I assure you, with practice and patience you can become a well versed measuring machine! I want to touch on some practical ways to determine if measurement tools are working correctly. If you went out and bought a cheap or expensive set of micrometers with measurement capabilities ranging from 0-6” how would you know they are accurate right out of the box? Is the manufacturer responsible for insuring they are accurate? Do they ever lose accuracy? Does the fact they were either cheap or expensive matter? The answer to all these questions is that prior to use, regardless of price or quality, most measurement tools will require calibration. Calibration is the practice of checking or setting the accuracy of a measurement tool to a known value. For measurement tools such as calipers and 0-1” micrometers simply ensuring the tips of the tool are clean, closing them together, and making sure the tool reads zero may be all that is necessary. This is a fairly easy method of calibration for these two tools, but isn’t possible for measurement tools where the tips don’t close together all the way (ex. 2-3” micrometer) or the tool has tips that extend outwards (ex. dial bore gauge). For these situations measurement gages are necessary for accurate calibration. Calibration gages (sometimes called standards) come in several varieties depending on tool application. The most common and applicable to engine inspection are gage blocks and ring setting gages. Gage blocks are small blocks of steel (more expensive variants come in other materials) which have been finished to extremely tight tolerances. Gage blocks are toleranced into several different classes. For engine inspection the most accurate measurements that must be made are to 0.0001”(0.025mm). In the measuring world the rule of thumb for calibrating tools is to use a standard which is at the minimum four times as accurate as the tool. So for a micrometer which is accurate to 0.0001” a gage block with an accuracy of at least +/- 0.000025” should be used. What the measuring world does and what the at home engine builder can do feasibly are two different things. For the majority of us our measuring abilities will get in the way of our accuracy long before the gage block used to calibrate the tool has any effect. For this reason I would suggest that using the standards which come with the tools will be fine and not splitting hairs over not knowing the exact accuracy of the standards. If you are shopping for a 0-6” set of micrometers most decent sets will come with standards blocks. The standards will usually come in 1, 2, 3, 4, and 5 inch sizes so all the micrometers can be calibrated at any time. Ring setting gages are similar to gage blocks and are also used for calibrating measurement tools. They are, as the name suggests, rings that have been machined to very fine tolerances. Usually instead of having a tolerance range that the ring falls into the ring will be stamped with the exact diameter it was machined to. A measurement tool such as a dial bore gauge is then calibrated to the exact diameter of the ring setting gauge. Ring setting gages are generally quite expensive as they are challenging to make accurately. Okay, I Understand the Importance of Calibrating My Measurement Tools. What About Making Precise and Repeatable Measurements? Precision gets complicated pretty quick because you have to factor in the measurement tool, temperature, and user taking the measurements. These three variables are difficult to separate completely. However, out of the three variables the user is usually the most likely variable to have a large influence on the precision of the measurement tool. In order to make precise and repeatable measurements it is important to do as many things the same as possible. Here are some things I recommend doing to make sure your measurements are as precise as possible. 1. Make sure the temperature in the room you are measuring is at 68°F (20°C). 2. Try to perform measurements of a part or set of mating parts in a short time period. There’s no need to rush the measurements or to measure all the parts in one day. It’s not that critical but, for example don’t measure the diameter of the piston one day and then wait to measure the bore of the cylinder. That doesn’t make sense. 3. When using micrometers use a micrometer stand to secure the micrometer in place. Not only will this make positioning the part easier and the micrometer easier to read it will also keep the heat of your hands from warming the micrometer. Remember thermal expansion? Believe it or not there are actually studies out there detailing how body heat makes a micrometer expand in length. It’s a minuscule amount but nonetheless worth mentioning. 4. A lot of measurement tools are operated by feel. When working with these tools try to be as consistent as possible when turning the handles. The amount of pressure you apply can have a big effect on the final measurement. For example, the difference between a part that drags hard through the tips of the tool versus one that drags but is soft in feel could be several ten thousandths of an inch. 5. Use your fingertips and a light grip. The fingertips are one of the most sensitive parts of the human body. As such they can be utilized to feel subtle variations in measurement. 6. Instead of just taking one measurement take 3-5. This is something you should definitely do when calibrating your measurement tools. By taking multiple measurements you’ll quickly get a feel for how precise your measuring is. If you are all over the board there is a good chance your technique is inconsistent. If you are within a ten thousandth or two each time you are on to something. For important measurements like cylinder bore diameter, taper, and out of roundness take 3-5 measurements. Then take the average of these measurements and use the average as your final measurement. 7. If you are struggling to determine if your measurement tools are working properly compare them to another known good set. If the two sets are not reading close to identical there is probably a problem with the unknown set. 8. Compare your results to those of someone with a lot of measuring experience. If a seasoned machinist can get your measurement tool to repeat to a ten thousandth of an inch it is probably not the tool. If you have the opportunity to get help from a machinist or someone fluent with measuring watch them carefully. Ask them questions, study how they work the tools, and learn from them. 9. Be patient and take your time. Rushing the measurement process is not a good idea and can lead to silly mistakes. You need to be in a state of mind where you don’t feel rushed and don’t mind taking the time to do a thorough job. 10. Write your results down! Write down everything clearly from the calibration measurements, any calculated averages, and measurements of specific parts. By writing things down you can easily work backwards to see if a mistake has been made somewhere. By keeping in mind accuracy, precision, and resolution you are well on your way to precision measuring like a pro. As I stated earlier, this takes a hefty amount of practice and patience. In my next post Precision Measuring For The At-Home Mechanic // Part Two, I will be discussing in complete detail how to properly use specific measuring tools. There is a definite finesse to using each of these tools as you rebuild your engine, and as you just learned in this post there are many factors that contribute to a precise measurement. Part Two will be posted to the DIY Moto Fix Website next week and you can have it sent right to your email inbox by subscribing to my eNewsletter by clicking below. Subscribe To The Moto Fix eNewsletter Thanks for reading and happy wrenching! -Paul Olesen Moto Mind - Empowering and Educating Riders from Garage to Trail www.DIYMotoFix.com

Paul Olesen

Paul Olesen

 

Workshop Basics For At Home Engine Building

I like to compare building an engine to performing open heart surgery. The precision and organization that goes into open heart surgery is exactly the mindset you need as you begin to rebuild your engine. Just like an operating room, I require my workspace to be as clean as possible. In the industry, companies have dedicated rooms just for engine building. These rooms are equipped with dust management systems, precise temperature control, and spotless work surfaces. I don’t expect the home mechanic to have this intense of a setup, but you should aim to have the cleanest work area possible. One of the first things you will need to do is make sure the area you are working in is free of dirt. Use a vacuum to suck up dirt from work surfaces and the floor. Occasionally you’ll drop a part on the floor and the last thing you want is for it to wind up covered in dirt. This should go without saying, but don’t try building an engine where metal is being ground or cut. The temperature of your build area is also important. Parts are designed, manufactured, and inspected at 68°F (20°C). This means that in order for you to correctly measure a part during your build it should be at the standard temperature of 68°F. As long as you are close to 68°F you’ll be fine, however building an engine in a cold unheated garage in the dead of winter may not yield accurate results. Conversely, measuring parts in a sweatbox of a garage without airconditioning will not work that well either. Let’s move on to other aspects of the workshop that are important. Until recently, my workbench was old and the work surface wasn't the smoothest or cleanest. It is difficult to get all the dirt out of plywood so I like to line my plywood tops with paper or cardboard then replace as often as necessary throughout the build to ensure cleanliness is kept up. This practice ensures I’m not working on a dirty surface and exposing parts to unnecessary dirt which could cause scratches or damage. If you have the luxury of working on a laminate counter top or other hard smooth surface more power to you. Just remember to wipe the surface clean as you go to keep dirt to a minimum. Lighting is one area that can be overlooked for many home mechanics. Make things easy on your eyes and be sure you have a good source of lighting where you are working. This way you’ll easily be able to see the wear in used parts, accurately read measuring equipment, and correctly assemble new parts. I prefer good overhead lighting when available, but when unavailable good portable lighting can be just as effective. Portable lights affixed to stands that can be raised above shoulder level work well. Tool storage and how you choose to handle your tools throughout the build comes down to personal preference. My tools are stored in a two level rolling toolbox. I can easily roll my toolbox from the motorcycle lift to my workbench once the engine has been removed. Instead of putting tools away after I’ve used them for a given task I like to leave them out. By keeping them neatly organized I don’t have to go digging for them later down the road. The tools I frequently use are then set either on my workbench or on a rolling cart so I can quickly grab them throughout the build. Allocating space to set parts aside as they are disassembled is important. Laying out and keeping a completely disassembled engine organized requires some room. A 3’ x 4’ area dedicated to storing disassembled engine parts will usually work. Alternatively a rolling cart with multiple levels is a handy option as it allows better organization and you can wheel parts around with ease. Make sure you are storing parts on nice smooth soft surfaces. Laying out parts on something like a grated metal shelf or work top wouldn’t be a good idea as the parts could be damaged when they contact the surface. This is especially true of gasket surfaces on covers which mar pretty easily. Another must is to never stack parts on top of one another. Make sure the area you have chosen to lay out parts is dirt and dust free throughout the build. Do you have any workshop tips you'd like to suggest? Leave a comment below and share your tricks with the TT community! Moto Mind - Empowering Riders from Garage to Trail http://www.DIYMotofix.com

Paul Olesen

Paul Olesen

 

What Tools Do You Need To Correctly Rebuild A Dirt Bike Engine?

To continue on our engine rebuild journey I want to discuss tools this week. Use this post as a basic idea of what tools are required to do a complete engine rebuild at home. Now I know a lot of you probably have a pretty good idea of what is required, but I want this to be a quality resource for anyone just starting out and considering working on their own engine. Below I have shared all the tools required to do a full rebuild, top and bottom end, on a Honda CRF450R. Understandably each make and model will differ slightly due to parts, however I believe this example will provide a great overview of what is necessary to complete a highly thorough rebuild. In addition to the list here, I put together an Amazon wishlist of "Engine Rebuilding Tools" that you can check out by clicking HERE. I want to point out that I am in no way affiliated with selling any of these tools nor do I guarantee that you will find the cheapest prices by purchasing tools off of this list. I will take responsibility for any impulse buys and am willing to act as a scapegoat should you have to explain why you spent a load of cash to your significant other. Amazon has a very nice way of bundling all the tools into one place so you can get a feel for the individual prices. I added tools to the wishlist based on my own experience with them (I own a good portion of what's on the wishlist) and looked through user reviews on the tools I don't own. When creating the wishlist I definitely kept budget in mind, but these are not necessarily the cheapest options. This tool list is a good place start if you're looking to add to your toolbox. While some may argue or believe they need Snap-On grade tools, I believe most people can get away with a good economical set of tools. There is no-doubt that mechanics who work with their tools everyday need high quality tools, however the at-home mechanic isn't experiencing the intense workflow of a professional mechanic and will use their tools much less over time. This makes it more economical to buy lower priced tools and replace them slightly more often than the big buck tools. The trick to getting tools you'll be happy with is knowing where to spend a few extra bucks for a quality tool. I believe about 90% of all the tools you need for working on a motorcycle engine can be had pretty reasonably. The remaining 10% is where a little time spent researching good options and spending a little extra money comes into play. The 10% Final assembly tools (torque wrenches), specialty tools, and measurement tools are the three categorizes where you should look for good quality tools. Reassembling an engine or other parts with torque wrenches that are inaccurate can lead to big problems if you end up over tightening bolts, stripping threads, and damaging parts. Not investing in specialty tools which allow you to disassemble and assemble parts correctly can also lead to damaged parts. Finally, precision measurement tools are what determine if your engine components, such as cylinder and cylinder head, are in spec or need to be serviced. Measurement tools are a very special breed of tool. It takes practice to learn how to use them proficiently. If not used properly, these tools can result in inaccurate measurements. If I were just starting out learning how to rebuild engines I would seek the help of a professional machinist or builder to help with the portion of the rebuild where you need to inspect the cylinder and cylinder head. These are two of the most important parts on an engine and incorrectly assessing the condition of these parts can lead to premature failures. For builders just starting out, experience could be gained by measuring less important parts. From there you can work your way up to becoming proficient at measuring the cylinder and head. Quality measurement tools such as those offered by Starrett, Mitutoyo, and other industry leaders, can be extremely expensive for the home mechanic to buy new. There are other options such as buying used or buying brands such as Fowler, Brown and Sharp, or Anytime Tools to name a few. In my experiences the quality offered by the lower cost brands has been quite good and when I have compared some of my cheaper measurement tools to the industry standard brands they have done very well. Like all tools, measurement tools are an investment and determining if you'll get enough use out of them to warrant the cost must be determined on an individual basis. For folks just starting out I think having a a nice pair of calipers, 0-1" and 0-2" micrometers, and a set of lash gauges will do your rebuild justice. Do you have tools you want to recommend? Have something to add? Please leave a comment below. For those who have been interested, our Honda CRF450 Bottom End Full Engine Rebuild Video Manual has launched. You can check out all the details, including a preview of the video manual HERE. Moto Mind - Empowering and Educating Riders From Garage to Trail http://www.DIYMotoFix.com

Paul Olesen

Paul Olesen

 

How Much Does It Cost To Rebuild A Four-Stroke Engine?

How Much Does it Cost to Rebuild Your Four-Stroke Engine? What costs are associated with rebuilding your engine? This is a topic that I see over and over again here on the forums and I have decided to take it head on. This question has many layers to it, and in order to answer it properly there are a few more questions that need to be asked. Are you going to let your wallet get roosted at the shop and trust that the mechanic does their job? Are you going to brave the tool box and try do it yourself? The bottom line is if you want to save money and be sure that your bike is well taken care of the answer involves a little bit of both. To start I wanted to get an accurate picture of what shops are charging across the country to do a full rebuild, top end servicing, and other various maintenance tasks. This includes what the OEM dealers are charging and recommending as well as the non-dealer private shops. Along with the OEM vs. Non-OEM differences I wanted to see if there were any differences between geographical regions. I guarantee you, this experiment was nothing short of interesting. The Plan: I would call eight shops in total across four different regions of the United States. In each region I would call one OEM shop and one non-OEM shop. To be a bit more specific, the regions I focused on were the Midwest, the South, the East coast, and the West coast. All the shops were found using Google Maps and then selected based on the quality of their website appearance. If I found on their website that they were qualified to do engine rebuilding and servicing, then I considered them a worthy candidate. Another grading system I used to select which shops to call was the Google rating they had when you searched for them online. This includes the number of reviews and a 5 star rating scale. Whichever shops in each region had the most reviews and the highest ratings I selected to experiment on. As consumers we are drawn to professional well-organized websites that have testimonials that instill trust, so all else being equal, I decided these were the best ways to select the shops for my experiment. The Scenario: Along with getting prices for services, I wanted to see what shops were recommending when it came to service intervals and part replacements. The best way to do this was to introduce myself as a fairly new rider who just bought an eight year old bike. In my eyes, new riders are the most vulnerable when it comes to being mislead or price gouged so they would be a perfect subject to use for the call. I also assumed that shops would be more willing to answer my “new rider” questions because it ensures that they help beginner riders get going in the sport, as well as want to come back to their shop come service time. I began each call by raising concerns about the integrity of the bottom end of the engine. I stated that the bike was a 2006 Honda CRF450 with around 200 hours on it. I asked if the bottom end should ever be replaced and what a full rebuild would cost. I also asked if there were any tests that could or should be performed to check the integrity of the bottom end. Once my bottom end questions were addressed, I proceeded to ask about the top end and how often the piston should be replaced. I asked about the price of top end services and what that service entailed. I also asked specifics about the inspection of cylinder head and if the valves ever need to be replaced. The Outcome: Naturally conversations shifted and answers took me by surprise, thus making simple side-by -side comparisons of all the shops’ answers impossible. So for your enjoyment (or dismay) the most fair and accurate way is go through each individual shops’ conversation with me ,summarize them, highlight their price, and recommendations. Prepare yourself for the good, the bad, and the ugly. Midwest OEM I introduced myself and explained to the service department that I had a 2006 Honda CRF450 that I was considering having fully rebuilt. I was a new rider, the bike was raced from time to time by the previous owner, and it had over 200 hours on it. I wanted to know what a full rebuild would cost and if they thought it was necessary. The service department asked me a few questions about the top end and if there was any damage to the bike, and asked if I wanted just the top end “freshened” up. I said no, there was no damage to it. I replied that since the engine had so many hours on it I was worried about how long the bottom end would last. He put me on hold for about 10 seconds, then picked up and told me that a full rebuild would be, “very, very expensive, many hundreds of dollars,” then asked for my name and number, and said he would get back to me on a price. It’s been over 10 days and this shop still hasn’t returned my call. What are my thoughts on this? Out of all the shops I phoned I felt like this one may have been the most fishy. No other shop I called willingly let me talk them into rebuilding my bottom end and they all told me it wasn’t necessary. My conversation with the service department was short and they really didn’t have much advice for me but were willing to do the work. “Many, hundreds of dollars?”, a full rebuild will most likely cost over 2000 dollars. I don’t think the right questions were asked on their end about the maintenance history of the bike, the price was misleading, and from what I gathered they didn’t have much experience working on this particular model. West OEM I introduced myself, my concerns with my ‘06 CRF450, told them about the 200 hours on it, and asked about a full rebuild or any advice they could offer concerning caring for the bike. The shop guy who answered said with 200 hours that the bike has to have had a few top end replacements done already. I questioned him on the need to do the crank bearings and he immediately said, “Not necessary, not necessary. I’ve got an 02’ myself and it has the original crank in it.” He then went on to assure me that all the problems come from, “...top-end stuff. Valves and pistons, not crankshafts.” But then he immediately contradicted himself and someone he knew blew a crank out, “But to predict it and just throw a crank in because of maintenance, that’s all up to you. That’s a couple thousand dollars worth of work.” Instead he suggested just doing a valve adjustment, “With a valve adjustment we could tell what size shims are needed to adjust the valves and from there tell how much wear and tear is on the top end.” I then asked if there really was no way to know when a crank will blow out and he said, “It’s more about maintenance, making sure the oil is clean, and things like that that take care of the bottom end. If you blow a clutch up and don’t clean out the bottom end properly those pieces can contaminate the bottom end and cause other problems. If you’ve been taking care of the bike and changing the oil then the bottom end should be fine.” He then told me that the piston needed to be replaced every 15 hours of riding per the factory service manual recommendations. He then offered to do the valves for me, but said we might as well get a new piston in while we are at it. I asked him how much this would cost and his reply was, “Depending on what’s going on you’ll spend 500, 600, or 700 bucks. I’d say I’d have 500 to 1000 ready to go depending on what’s wore out. You know 700, 800 bucks is usually pretty close.” I then asked him about the service interval for the valves, just to get a picture on how much this would cost me over time. He then stated that it was related to the maintenance of the air filter, “If the air filter isn’t maintained properly, it has a little rip in it, or gets a little dirt in it that is what wears those valves out. You can have bad air filter maintenance and wear those valves out in one ride because they are titanium and hard coated. Once that hard coating wears out then that valve wears out extremely fast. So if the engine ingests a little bit of dust or dirt then the valves can go away pretty quick. Stainless valves are a lot more durable. The valves that we put in it are out of the TRX450.” I thanked him for his input and said I would think about it. My thoughts? I thought that this shop was the best out of all the shops I spoke with. I think the service guy did the best he could to help me however I still think there were some contradictions and flaws with the advice he gave me. One of the troubling things that is a theme throughout my conversations is the bottom end question. All the shops were adamant that it’s not necessary to replace the crankshaft or bearings yet as highlighted in this conversation even the service guy knew someone who had a bottom end let loose. So as consumers the question has to be “should the bottom end ever get replaced or not?”. This in my opinion is dependent on the type of riding that is being done. Being told the piston must be replaced every 15 hours bothered me a little bit too. I understand that the factory service manual states this and I know that is the reason the service guy told me this however the service manual intervals are for bikes that are being raced. I wasn’t asked how I was riding the bike and think for anyone not racing replacing a piston every 15 hours is a bit excessive and expensive. The service man’s general info on maintenance and the repercussions of not maintaining the oil and air filter are spot on along with his input on valve maintenance. The shop rates while fluctuating I think are in the ballpark for what someone might expect to pay since the amount of work required on a top end can be minimal or significant depending on the condition of the engine. South OEM Service manager was out to lunch. A message was left but my call was never returned. My thoughts? As a business I would think it could be profitable to return a customer’s phone call? East OEM I introduced myself and my bike, as well as my concerns about servicing it after 200 hours, as usual I asked for a full rebuild, raised concerns about the bottom end, and if the crank needed to be replaced. The shop told me right off the bat that you never need to touch the bottom end on a four-stroke. It never needs to be serviced or replaced. I asked again, just to be sure, and brought up the fact that I knew that some two-strokes could come out of true, and he assured me, “Nope, nope, that’s the beauty of having a four-stroke.” So then I raised concerns about piston replacement and the valves, to which he replied, “Valves, yeah, not so much replacing them. Just making sure they are in spec. What year did you say? 06’? I said yes and he put me on hold for two minutes. When he picked up he informed me that on my make and model I need to come in at least every 10 hours of riding to have the cylinder head inspected and perhaps the valves adjusted. It would cost me around $160 each time, or $200 if the shims needed replacing. (This service involved disassembling the head and using a valve guide gauge to check the diameter of each valve guide) Cue my mind exploding. Then he went on to tell me that if I just bought it to get it done regardless, “Because you know, I think something in there is aluminum on the older models and they heat up and not hold up and then you get the cherry red exhaust pipe. That’ll end up messing up your head.” Okay… He also told me that, “the newer ones were made with magnesium, and like, tougher things, so, you know.” (Magnesium is softer than aluminum, has a lower melting point, and unless combined with another alloy would never be used for any part of a cylinder head by the way). I asked him about the piston, to which he replied, “Now that’s one of those things like the crank. Being that it is a four-stroke it is not taking a beating like the two-stroke bikes. You leave that alone. If it goes, then that’s something that happens but there’s no replacing those either. It’s mainly all valve jobs on that thing.” I thanked him for his wisdom and time. Where do I even begin on this call? Sometimes I think the folks answering the phones at the shops feel they must give you at least some advice, right or wrong, when it would be much preferred if they just conceded that they don’t actually know. In this case the man I spoke with chose the route of telling me lots of wrong things. This call was by far one of my worst conversations, and I was left wondering how the service men that were fielding my questions are in the roles they’re in. The advice on never changing the piston is wrong, the head does not need to be taken off every 10 hours to check the valve guide bores, and I’m certain magnesium is not the saving grace for the newer Honda cylinder heads. Midwest Non-OEM I introduced myself and my bike, I asked about the bottom end needing servicing, what it might cost to service the piston and the valves, and I told the guy I was trying to familiarize myself with maintenance schedules. The guy told me it all depends on parts availability and pricing. He said his shop charged $60 an hour. I asked him again about the crank or the valves, trying to get some more information on service intervals, etc. But he replied curtly that it would be about an hour and a half of servicing, so $90 in total. I thanked him and hung up. My thoughts? The theme I noticed with the non-OEM shops is that they were all much less familiar with my particular make and model. This I believe is due to the fact that they work on anything and everything and don’t see the same type of bike frequently enough to proficiently give sound advice. In the case of this shop my main questions were dodged and the best I could do was get a shop rate and a price for adjusting the valves. The person on the phone was not particularly helpful nor pleasant to speak with making it hard to want to continue my conversation or consider doing business there. West Non-OEM Per usual I introduce myself and my bike, tell them I’m a new rider, ask about the bottom end and other services. The shop guy told me that the best way to know would be to bring it in and have them look at it. He took a moment to speak to the service department and another guy got on the phone with me and told me, “You don’t have to check the bottom end at all. It’s usually all top end stuff. Unless your bottom end is going the only way I can check that out is by tearing your motor apart. And there’s no reason you should be tearing your motor apart.” He asked me again about the history of the bike and cut me off mid sentence and said that an oil change and valve servicing would be imperative. I asked again about piston replacement and he told me that it would cost $1000 to $1500 minimum. What? He told me, “Yeah, because I have to tear down the top end of your motor and rebuild it.” He then quizzed me about the type of riding I was doing, two points for them, and I told him I wanted to do a little bit of motocross practicing, but then he cut me off mid-sentence again and told me, “I think every 15 or 20 hours you’re supposed to have the valves inspected.” I started to ask a little bit more, but he curtly said, “Is there anything else cause I got customers standing in front of me.” Whoa, okay. I asked him one last time on the cost of the piston replacement and if that included the valves being checked to which he said, “Don’t hold me too that. That’s why I said it could be 1000-1500 dollars. It could be a little bit more.” I thanked him for his time and hung up. My thoughts? The service man on the phone was pretty rude, asked a few of what I consider the right questions, and then gave me an awfully high price to overhaul my top end. I wanted to know more about what his top end overhaul entailed but he clearly didn’t have time to help me so the conversation was cut short. As rude as the man was I would think it would be difficult to attract business if he acted that way all the time. South Non-OEM After introducing myself and my bike, asking about the bottom end, the piston, etc. They guy told me to just take it to a Honda dealership. He said there was no way of checking the bottom end without tearing the engine down. He told me with approximately 200 hours on the thing, “I wouldn’t be that concerned about it.” He prompted me again to call a Honda dealership to get more maintenance interval information, but that his shop could perform any of the work needed. Right. I asked him again about the cost of replacing the piston. He stalled and said that he would have to get back to me on that one. He took down my number and told me he would call me back. It’s been over 10 days and the shop hasn’t returned my call. My thoughts? I appreciate this shop’s honestly. The person I spoke with wasn’t that familiar with my bike and didn’t hesitate to try and point me in the right direction by directing me to a dealer. The advice he gave was indicative that he didn’t know a whole lot about the bike. While it’s possible he was fully capable of performing any work I would prefer the person doing the work know a bit more about the bike. East Non-OEM I introduce myself, my bike, ask my gamut of questions. The shop guy tells me, repeatedly, you can’t check the bottom end without removing the top end. So I ask about the top end and tell the shop guy, “Well the previous owner said he did it every 40 hours and there are about 20 hours on it since he last did it. Was his service interval right or should it have been done more or less?” He asked about the type of riding the last owner was doing, two points for this guy, and I told him a little bit of racing, to which he replied that those intervals were normal. So I asked how much it would cost to overhaul the top end and he told me, “Well the cylinder head has to be sent out so you’re probably looking at around 750 bucks.” He asked me how I was planning on riding the bike and I informed him just around on the trails, nothing too hard, and his advice was, “Yeah, I would ride it. When it starts losing power and becomes hard to start that means the valves are going to need to be looked at and at that time we can check out the top end.” I thanked him for his advice and hung up. My thoughts? I’m going to assume the service man was talking about checking rod end play, small end diameter, and axial free play when he said the top end would have to come apart to check the crank. With the crank still in the engine the run out wouldn’t be able to be accurately checked. As I wrote in one of my previous posts about service intervals offering specific advice on when to service a particular part is difficult. It was refreshing not to hear every 15 hours or never replace the piston. Whether every 40 hours is right or not would require further information on the experience level of the past racer. The cost to service the top end sounded like a competitive price especially if any head work was going to be done. The service man’s advice on when the bike might need attention was also in alignment with what I have previously written. As you can see the information provided by the various shops was sporadic, lukewarm, and in some cases - plain wrong. This is a complete shock to me, I have to be honest and say that I expected a bit more out of these shops, OEM and non-OEM alike. I assumed that the training of those running and working in these establishments was to a high enough level that the only thing that would vary would be the cost of a particular service. I never imagined the advice and service intervals would be so terribly misleading. This whole experiment became a can of worms, but I am glad I took it upon myself to do it because it shows me that educating myself and working on my own bike all these years was the better choice. Based on the answers the shops gave me, it is imperative that consumers do some serious research before selecting a shop to perform internal engine work. You need to be asking the right questions and the shop needs to instill the confidence that they are capable of doing the work, before you hand over $2000+ for a full rebuild, or $750 to $1500 for a top end overhaul. The lesson here is if you want a shop to do the work, take the time to be absolutely sure you are getting your money’s worth and that they are a knowledgeable source. Based on my experiences dealing with the shops I think a consumer can greatly increase their chances of finding a great shop by searching for shops that specialize in a particular make, model, or segment of the market. For example I would expect the competency of dirt bike specific shops to be much higher than the all make and model variety. Here’s the thing about running a shop though- the prices they charge are justifiable because that high price is what keeps their business going. I understand that and I wouldn’t mind paying them if the majority of theses shops could provide a concrete answer to my questions. The problem for some folks is that power sports are expensive enough, without bringing in a mechanic to help repair their engine. If a consumer can't afford to have a professional fix their bike they either have to do it themselves or they end up leaving the sport. With land closures, environmental regulations, and the high costs associated with dirt biking - the sport is already in decline. We cannot afford to lose riders because they don't know how fix their own bike or can't afford to bring it to a shop. I see this as a serious issue because the life of this sport is dependent on a bike that runs and a rider that is excited to get out and tear it up. So how do we keep the money in our pockets and make sure our bikes are cared for properly? After seeing for yourselves the varying degree of information given by shops some of you might be wondering why I haven't disclosed the names and locations of the shops I called. In some cases I would like to, but the point of this article is to outline the costs, varying degrees of knowledge, and competency of the shops. I want this write up to be an educational insight into the industry and don't intend to harm individuals or businesses. As consumers you are the ones that need to decide for yourselves who does your work by asking the right questions and educating yourselves about your machines. There is something indescribably cool about knowing how your bike and engine go together. Whether it’s saving yourself a chunk of change, knowing how to care properly for your bike, or just learning something new and mastering it. So how much does a full rebuild cost you when you do it in your own garage? When you are using OEM parts, which includes all new bearings throughout the engine, a cylinder head, new valvetrain, new crank, new piston, new cam chain and tensioner, and a freshly honed cylinder, the cost comes to $1300 to $1500. I have a complete parts list you can check out by clicking HERE. So compare that price to $2000+ and suddenly doing the work yourself doesn’t seem like such a bad idea, also add in the coolness factor of learning how your bike goes together and knowing you rebuilt an entire engine on your own. Another thing to consider is that you will have this knowledge forever and it will extend the life of your bike(s) and your bank account for many years to come. And how about the cost of a top end overhaul in your own garage? This could run you as little as $260 for a piston replacement, which includes a new piston, rings, circlips, head and base gaskets, and a freshly honed cylinder. Pretty inexpensive right? On the flip side a severely worn out top end which needs every bell and whistle replaced, aka the cylinder, the head, and valvetrain components could cost you $900 in OEM parts as well as machine work being done on the head and cylinder. Again, compare this to the $750 to $1500+ range for an in-shop piston replacement. The top end parts list can be viewed HERE. These at-home mechanic perks are dependent on you putting the bike together correctly though, because if you don’t it can cost you big time. When I first started tearing into my own bike I made a lot of mistakes that I wish I could have avoided because it did end up costing me in the long run. Looking back now on those rookie rebuilds, after my education as a powertrain engineer and having designed and built an entire race bike, there were so many things I could have avoided. The only thing available to me back then was a factory service manual, but without good pictures and a well written step-by-step process it was a complete headache. For someone who is just getting into the whole rebuild world, those manuals are like trying to read another language. All I kept on wishing is that I had a mentor to learn these things from properly. Trying to watch free how-to videos online is a complete mess as well. After watching as many of these free videos online that I could find, as a professional I wish I could shout from the mountain tops to beware. These videos are poorly made, the information is spotty at best, and the mistakes that can be accrued from trying to reference them can be costly. So how and where do you even begin to learn how to rebuild correctly? When I truly began to learn how to fix things the right way, was when I started pursuing an education and career in the motorcycle industry. By working with highly skilled and experienced engine builders and engineers on a vast array of different engines, I learned that attention to detail is such an important aspect of rebuilding a healthy engine. Another key to success was having the right tools (look forward to a future blog post on this) and taking the time to measure things precisely (again, a future blog post). As I began to rebuild engines more and more, I realized that there are steps in which you need to trust a professional to do the work. For any at-home mechanic guy or gal, you can honestly do 90% of the work yourself and save a huge chunk of change. That other 10% can be farmed out to a competent machinist or shop at a miniscule fraction of the price versus trusting a shop to do the whole thing. So how do we bridge that gap for the riders who want to learn how to rebuild their own engines the right way and save themselves money? My aim is to empower riders from garage to trail. That means teaching you how to professionally tear open your own dirt bike so that you save money and know the work is done right. DIY Moto Fix is a business that wants to work with riders that want to learn how to work on their own engines, learn something new, and become an at-home mechanic master. Maybe you don't want to pay the high costs associated with a professional shop or you don't trust the work performed by professional shops. Perhaps you're just starting out and don't have a mentor that can teach you the ins and outs of rebuilding your own engines. I feel as if there are a lot of riders out there that would love to do the work themselves, if they could only find a credible source to learn from, and that’s where DIY Moto Fix comes in. Learning the Professional Way: We put together high quality HD how-to videos that teach you how to professionally rebuild your own engine. These videos are instantly downloadable, you can watch them on your mobile phone or home computer, and they come with a wealth of information that teaches you about your engine step-by-step. The beauty of these videos is that they include absolutely everything you will need to do a full rebuild - all the necessary torque specs, tool call-outs, new part numbers, and sequences. It completely eliminates the need for a service manual, any online searching for tips or tricks, or the endless quest to reference dealer part numbers. In addition, we teach the how and why behind each step so you come away with a better understanding of how the engine goes together. These videos are a credible source of information created for the everyday rider. Think of them as an Engine Rebuild Master Class. I am so excited to bring this level of knowledge and skill to the people who could benefit from it the most. This is the way we keep this amazing sport alive, by empowering and educating ourselves and saving money. If DIY Moto Fix could create an army of knowledgeable at-home wrenchers - we could die happy. Conclusion on Rebuilding Your Own Engine: When you think of the amount of money you can save over time by learning how to rebuild your own engine, when shops charge between $60 and $100 an hour, we’re talking thousands upon thousands of dollars. Another way to look at it is the amount you would save on one full rebuild at a shop is equal to the amount you could invest on the proper tools to do it yourself, over and over again. I would love to invite you to become a professional grade at-home mechanic and learn the correct way with DIY Moto Fix, whether you are a rebuild rookie or someone who is working to become a DIY master. If you are a CRF450 owner, someone who is interested in learning more about full engine rebuilds, or our master rebuild class - sign up by clicking the button below and we will send you all the information you need to get started. Send me the FREE Four Stroke Engine Rebuild Tools Guide For those of you that enjoy reading about engine rebuilding, I published a comprehensive book which details the fine intricacies often overlooked by amateur engine builders. The book covers a variety of topics including diagnoses, how engine parts are manufactured, precision measurement tools, disassembly, inspection, and correct assembly techniques. Do you have a shop horror story you want to share? Did you recently have your engine rebuilt and want to share how much it costs? Do you like the idea of educational how-to videos that teach you how to rebuild your engine? What other things could we produce for you that would help you as an at-home wrench and rider? As always, I enjoy hearing your thoughts and comments. Moto Mind- Empowering and Educating Riders from garage to trail DIYMotoFix.com

Paul Olesen

Paul Olesen

 

What is Hard To Start

First off, happy holidays to all of you out there! Thanks for taking the time to read my blog the last few months. I hope all of you have a happy and safe holiday season! Last week I talked about when is the right time to rebuild your engine. From that post a lot of good questions were asked in the comments section and this week I'd like to take some time to address one in particular. "Can you define what is hard to start?" Like a lot of things in our sport the answer to this is a bit subjective and I will share my thoughts on the subject. As always, you're encouraged to agree, disagree, or even better- share your personal thoughts on the topic. "What is hard to start?" - This seems like a shallow question at first, but considering all the variables it is tough to answer. "Is the bike hot?", "Is the bike cold?", "Has the bike been sitting for several weeks?", "Is it carbureted or fuel injected?", "Was it just tipped over?", or "Was the float bowl just drained?". In my opinion each scenario I've proposed invokes a slightly different answer. Combine this subjectivity with one's own personal starting routine and the ease of which the bike will fire up is going to be different for everyone. As a rule of thumb, if my bike takes more than five kicks to fire up as time progresses I will begin investigating possible starting issues. "What things might make a bike hard to start but not necessarily mean the engine needs to be torn apart?" - On most bikes there are two or three things that adversely affect how well the bike will start. On carbureted bikes the pilot jet circuit controls fuel flow from idle to about 1/4 throttle. The pilot jet has a very small orifice and clogs pretty easily. Once clogged the pilot jet is ineffective in delivering the necessary fuel to the engine and starting the bike becomes extremely difficult. Depending on make and model the bike may or may not be equipped with a decompression system that can be adjusted. For example, on the Honda CRF450 in order for the decompression system to function correctly a certain amount of clearance must be maintained between the decompression adjusting screw and the rocker arm. Occasionally this system needs to be adjusted similar to how valve clearances are checked and adjusted at set intervals. If the system gets out of spec and the correct clearance diminishes, more air escapes each time the decompressor opens the exhaust valve effectively lowering the compression of the engine. Old spark plugs are another culprit which might make a bike hard to start. If the plug is old and worn the spark will be weaker, making it more difficult to ignite the mixture. Keeping fresh plugs in the engine can greatly improve the bikes starting tendencies. Temperature and altitude should also be thrown into the mix here. If for some reason you moved from sea level to 6,000ft, fueling requirements for starting will be different since the air density varies in relation to altitude. As altitude increases the density of air (i.e. the amount of oxygen in the air) decreases thus requiring leaner jetting to make the bike run correctly. Air density also varies with temperature. The warmer the air is - the less dense the air is. So if you have summertime jetting and it's now wintertime and the bike is harder to start, it shouldn't be a surprise. The colder temps require richer jets to be installed for the increased air density. "How do I start a four-stroke dirt bike?" - Another good question that has lots of answers depending on the type of bike, if it is fuel injected, carbureted, hot, or cold. I'm going to assume most of the folks having trouble starting their bikes have carbureted bikes. I will provide my personal starting strategy I use on my CRF450 and if anyone is inclined to outline their strategy or provide alternatives to mine, feel free to leave a comment and share your knowledge. When Cold 1. Fuel petcock turned on 2. Choke turned on 3. Twist throttle to wide open three times 4. Roll engine over with foot until compression stroke is found (resistance will build up under your foot as fuel air mixture is compressed and piston will then be near TDC) 5. Kick repeatedly until bike starts (usually 3-5 kicks) When Hot 1. Depress hot-start lever 2. Roll engine over with foot until compression stroke is found (resistance will build up under your foot as fuel air mixture is compressed and piston will then be near TDC) 3. Kick repeatedly until bike starts (usually 1-3 kicks) Some of you might be wondering why the throttle is twisted wide open three times and this is a great question if you're unfamiliar with the internals inside a four-stroke carburetor. The majority of dirt bikes produced in the past 10 years come equipped with a Keihin FCR carburetor. The FCR carburetor is equipped with an accelerator pump. An accelerator pump works like a fuel bulb that you might find on the small engine of a power washer or weed wipe. As the bulb is squeezed a splash of fuel is pushed out. The accelerator pump was designed into the carburetors to smooth engine operation from low rpm low load scenarios to transitions to wide throttle. As the throttle is twisted to full-open, a plunger within the carburetor is actuated and forces fuel out of the "fuel bulb" through an orifice into the throat of the carburetor. For starting, the accelerator pump can be used to prime the intake tract with fresh fuel. Does it matter if I find top dead center on the compression stroke? - It isn't critical, but this is what I'm used to and what works best for me. I hope you found this write-up helpful and if any of you want to share your experiences feel free to leave a comment. Moto mind - Empowering and educating riders from garage to trail If you enjoy reading my blog be sure to subscribe by clicking the "subscribe" button at the top right of the page.

Paul Olesen

Paul Olesen

 

When to Rebuild Your Engine

This week I’d like to start a long series of posts on the proper way to rebuild a four-stroke engine. I will share with you a top to bottom rebuild where I go through the disassembly, inspection of parts, and reassembly of the engine. We’ll cover the top end, bottom end, and everything in-between. I’ll pass on the tips and tricks I’ve learned over the years from the people I’ve worked with in the motorcycle industry. Hopefully these tips will benefit you on your next engine build, save you money, and ensure you do things properly. Before I get into the specifics I want to discuss the importance of preparing for the rebuild. This week let’s talk when to tear into the engine. When to replace: Engine wear is directly related to RPM and mechanical stress so riders engaging in riding where the engine is on the rev limiter frequently, the engine is operating at a high RPM without any load on it, the gearbox is loaded or unloaded abruptly, or gears are selected hastily will require the rider or mechanic to service the engine frequently. Most of you will relate the scenario I have illustrated to motocross racing. At the top levels of racing, mechanics are constantly checking or rebuilding the engines to make sure they are operating at maximum power. Fortunately for most of us we are not riding or racing at the top level, so our bikes and engines last quite awhile longer. Unfortunately everyone’s scenario is different- depending on the type of riding you do, the environment you ride in, how often the oil is changed, etc. which makes it difficult to standardize or pinpoint any sort of service interval. As an engineer, mechanic, and rider my philosophy has always been to replace components preventatively before they fail. My reasoning here is that the costs attributed with a failed component are much higher than a replaced component. Let us consider a scenario where a piston fails. This could have been avoided had I replaced the piston and would have cost around $130. Instead it’s quite likely that the entire engine will need to be opened up and serviced, making the price of the repair extremely expensive. From an opportunity point of view, if any part fails on the bike while I’m out riding or racing I’ve lost out on a significant amount of time, a significant amount of points if I’m racing, and a wad of cash when it comes to paying to get to and from the venue. So apart from saving a small amount of money by not replacing a serviceable part, there is no upside to trying to prolong the life of a component. The ramifications of engine neglect are nothing to scoff at. The best way to determine when components need to be serviced is to keep careful track of the health of your engine. This means from the time of purchase to the day you sell you keep track of all the engine hours, maintenance, and repairs you do to the bike. By keeping track of engine time you’ll start to develop patterns and be able to establish your own service intervals. I wrote a nice article about maintenance logging which you can read HERE. Along with keeping a log from day one, I also like to do a compression test any time I get a new bike so I can establish a baseline for the health of the engine. As I put hours on the bike, if I ever become suspicious that the engine is down on power I can perform another compression test. Then I can quickly refer back to my first test to determine if I have lost any compression and might need to consider servicing the top end. The next thing you must do is pay attention to your engine. In most cases your engine will give you signs that it is time to service one component or another. Some common signs that may indicate your engine is due for servicing soon are: Hard to Start - This could be due to a fueling issue, ignition issue, decompression system out of adjustment, worn rings, worn valves and seats, a stuck valve, leaking gaskets, or cam timing that is off.
Engine Power has Diminished - This could be due to restricted fuel flow in the carburetor or throttle body, a clogged air cleaner, the clutch slipping, worn valves and seats, worn rings, a stuck valve, leaking gaskets, or ignition issues.
The Top End is Noisy - A noisy top end could be caused by a loose cam chain, out of spec valve clearances, a worn cam chain guide, or worn cam bearings.
The Bottom End is Noisy - A worn clutch basket which has started to rattle, damaged or stuck bearings, a worn bushing and needle bearing between the clutch basket and primary shaft, or gears which are improperly lubricated may all contribute to bottom end noise.
Blue Smoke - Blue smoke occurs when the engine is burning oil. Either the valve seals are allowing oil to leak past them or the piston rings are no longer sealing properly. Once the engine is warm very little blue smoke should ever be seen.
White Smoke - White smoke is emitted when the engine is burning coolant. This typically occurs when a head gasket starts leaking.
The Engine Consumes Oil - Oil is getting into the combustion chamber any time the engine consumes oil. Oil can either enter into the combustion chamber from worn valve seals or worn piston rings.
The Engine Oil is Creamy - Whenever the engine oil is creamy in color moisture is getting into the engine oil. While some moisture getting into the oil is normal excessive amounts are a cause for alarm and may indicate that a water pump seal is leaking.
The Engine Oil has Large Pieces of Metal in It - Metallic particles are common in engine oil but if larger metal pieces are found in the oil this is a cause for concern and should be associated with damaged components. An example of this could be finding fragments of chipped gear teeth in oil.
The Engine Vibrates Excessively - Excessive engine vibration may be caused by an out of true crankshaft, worn crank bearings, worn counterbalance bearings, a mistimed counterbalancer, or a loose clutch.
One last tool I want to mention that is helpful in determining the health of an engine is a leak down tester. With the piston at TDC and the valves closed (compression stroke) a leak down test pressurizes the cylinder to a specified pressure. A comparison is made between how much air is supplied to the cylinder and how much leaks out. The amount of air leaking out of the cylinder is used to determine the health of the engine. For example if 70% of the air is leaking out the cylinder there are serious problems! By carefully listening for the air leak(s) it is possible to determine the cause of the problem. I would really like to help you guys out and give you quantifiable numbers so that you know precisely when the right time is to rebuild your engine however I feel that by doing this I would be doing a disservice to a lot of you. I would either be giving you information that tells you to rebuild your engine too early or too late in its life which wouldn’t be good for anyone. As I mentioned before there are so many variables ranging from riding style, engine displacement, manufacturer, riding environment, and maintenance intervals that I can’t quantify all these things into one number for everyone or even several numbers for specific groups. Your best bet is to pay close attention to your engine, keep track of the hours on your engine, and learn as much as you can about your particular make and model so that you can begin to formulate a service interval schedule tailored to you. Questions, comments, or additional tips leave a comment below! Moto Mind - Empowering and Educating Riders From Garage to Trail If you'd like to follow my blog, click the "follow this blog" button in the upper right. I'd love to have you.

Paul Olesen

Paul Olesen

 

Riding Year Round in The North

ICE RIDING We're pretty excited up in the North that the lakes are frozen over. That means we can get the ice bikes out and start the winter riding season! We shot a short film over the holiday weekend detailing one of the two days we were out riding. I hope it makes you consider getting into the sport of ice riding or racing, because it's freaking awesome. WHAT YOU'LL NEED TO GET STARTED: Tires: Racing studs are classified into two categories, AMA screws which have a head height of 0.189" and Canadian screws which have a head height of 0.250". The difference between the two screws is that the Canadian screws with the taller heads grip better, especially when there is a layer of snow on top of the ice. Racing organizations in the US are starting to incorporate classes for Canadian screws, however racing classes mandating AMA screws are still predominant. For this reason I advise anyone just starting out and thinking about racing to start out on AMA screws so that more options are open later on if you decide to start racing. Tires can be bought studded or you can stud the tires yourself. Ice tires typically consist of the tire itself, the studs, and an inner liner which protects the tube from the ends of the screws. There is some technique behind studding the tires. Screw head orientation and insertion angle are important for traction and tire longevity. Kold Kutter has a nice video detailing how to install ice screws, which you can view below. For more detailed info on screws you can visit the Kold Cutter website. For professional tires I recommend Jeff Fredette's tires as they are what I have been running the past two years and can attest to the quality and traction they deliver. There are plenty of other reputable businesses studding tires as well, but Jeff's tires are my favorite. Jeff's tires can be found at: FPP Racing. Fenders: Fender kits can be bought or you can design your own fender setup using minimal tools and supplies. In my opinion any time you're riding in close proximity to other bikes, fenders are mandatory because they protect yourself and others from accidental tire to tire contact. When ice tires from one bike bind into another the result is catastrophic and unpleasant for both rider and bike. I'm sure you can imagine. The fenders ensure any tire contact between bikes is eliminated and the worst that will happen is the grinding away of the fender. Suspension: For the weekend rider and beginning racer, running stock suspension is pretty common. Shortening the shock and forks to lower the bike up to five inches is fairly common for serious racers because it lowers the center of gravity and makes the bike easier to handle. The suspension can also be softened slightly to help the bike adhere better to the ice when ruts and braking bumps form mid-race. Two-Stroke vs. Four-Stroke: Either a two-stroke or four-stroke bike can be a formidable weapon on the ice, however there are some differences I have found between the two. Due to the effects of four-stroke engine braking at times corner entry seems a little more difficult and entry must be assisted with modulation of the rear brake to help tip the bike in.
The free wheeling nature of the two-stroke allows for a little more natural corner entry.
Four-stroke bikes are a little more forgiving when entering a corner in the wrong gear and are more capable of tractoring out of the corner.
450cc size four-stroke and 500cc size two-strokes wear out tires faster than smaller displacement machines.
Two-stroke bikes have a lighter feel to them.
Four-strokes are a little more forgiving when tuning for cold weather than two-strokes.
Staying Warm: Ice riding provides a very good workout and staying warm isn't too hard if you use a little common sense. As with any cold weather activity layering up is essential. I like to wear thick socks, compression shorts, knee pads, and then a pair of sweat pants over the top for my first bottom layer. On top I wear a long sleeve compression shirt followed by my elbow and shoulder pads, then my chest and back protector. Next I wear snow pants, motocross boots, and my winter jacket. Around my face I wear a balaclava as well as a breath deflector inside my helmet to help keep my goggles from fogging. I equip my bike with handlebar mitts which allows me to wear a pair of regular motocross gloves. The handlebar mitts make or break the riding experience and with the mitts I've been able to get away with thin gloves down to around 5 degrees F. Racing: Racing typically consists of GP style tracks with both right and left hand corners, or oval tracks. GP races are either short sprint races or long three hour endurance races. One of my favorite races is the 3 hour Steel Shoe Fund race held in Cambellsport, Wisconsin. Last year over 75 teams entered the endurance race and all the proceeds went to aid injured flat track racers. Whether racing or spectating, this is definitely an event worth checking out. Steel Shoe Fund Race For finding races and riding spots local to your area I've found Google to be a powerful tool. Do a little digging and you are sure to turn up some quality riding or racing. Or if you are lucky enough to live on a lake, let the ice get up to 6 inches thick, plow a track, and have at it. I hope you enjoyed my break down of ice riding and if you have more info to share, a race you want folks to know about, or want to show off your ice bike please leave a comment. Together we can help grow and bring awareness to this awesome sport! Moto Mind - Empowering and educating riders from garage to trail If you haven't already done so be sure to follow my blog by clicking the button in the top right hand corner.

Paul Olesen

Paul Olesen

 

Tips on Buying a Used Motorcycle

TIPS ON BUYING THE PERFECT USED BIKE How many of you have bought your fair share of used bikes only to discover the moment you get it home that something is wrong with it? I have bought and sold a hefty amount of different types of vehicles over the years and recently started reflecting on some of my experiences. I have bought bikes that have run well, did not run at all, were partly assembled, or were complete basket cases. Sometimes there have been great deals and sometimes there have been total lemons. Occasionally I have even purchased bikes sight unseen and put my good faith in others to collect them for me. Has some of my behavior been risky when buying a used bike? Absolutely, but because of those experiences a lot of hard earned knowledge has come my way. With all the variables that get thrown into purchasing a used bike wouldn’t it be great if there was a way to increase your chances of avoiding a lemon? Over a month ago I started compiling all my used motorcycle buying advice to share with you. Now I know most of you are experts at buying used bikes, but these guides are great because it puts everything conveniently in one place, not to mention a printable checklist you can take with in your back pocket to reference in case you forget a few things. I began by writing down everything I considered vital when purchasing a used bike. Beginning with the research phase, I gave pointers on what to look into - prior to even browsing through any ads. Next I organized all the different things that are worthwhile to look over on the bike itself. In conjunction with that, I wrote down all the questions I think are important to ask the seller. Being allowed to test ride the bike is a huge thing for me also, so I went over all the different test procedures I use when test riding a potential bike. Last, but certainly not least, I included my tactics and tips when negotiating with the seller. These tips aim at the end result of hopefully heading home with a fantastic used bike in tow. After all this writing I ended up with two 30+ page buyer’s guides - one for dirt bikes and one for street motorcycles. These guides are the most thorough and detailed when it comes to purchasing a used bike I have found. I want to share eight of what I consider the top tips with all of you in my blog and ask that you download whichever free guide you need to learn the rest as there is just way too much information to post here. KNOW WHAT YOU WANT - RESEARCH MAKES & MODELS Thoroughly researching different makes and models will go a long way to ensure you get the bike you want. Familiarize yourself with the bikes you are interested in by researching and reading reviews on the particular makes and models you're interested in. By reading the reviews you will be able to gain a better understanding of what sort of performance you can expect from particular models, their shortcomings, and some things you can do to improve these bikes. CHECK THE VIN NUMBER Look on the frame of the bike for the VIN number to ensure that the bike is not stolen. If the VIN number is scratched off or the sticker has been removed, this is an indication that somewhere within the history of the bike it may have been stolen. If you have any suspicion that the bike is not clean, contact your local authorities and have them run a VIN number check. Refrain from exchanging any money until the the history of the bike is cleared. FEEL THE MOTOR Carefully feel near the engine for heat radiating off the engine to determine if the engine has been started prior to your visit. If the motor is warm it could indicate that the bike does not start easily when it is cold and the seller is trying to mask an issue with the carburetor or fuel injection system. If it is an older bike, a potential fix would be to clean and inspect the carburetor. If it is a fuel injected bike, there could be issues with the injectors, the fuel pump, the ECU, or the ignition system. CHECK HOW CLEAN THE MOTORCYCLE AND THE ENGINE ARE Often times if there is a problem or the motor is leaking, the seller will power wash the motor to hide the leak. If the motor or bike is suspiciously clean, when the seller runs the motor for you, double check around the engine for leaks that may appear. ASK THE SELLER WHY THEY ARE SELLING? This is a great ice breaker. This questions gives perspective into the seller’s motivation and reasons for selling. It also may give a glimpse into potential issues the bike may be having. HOW MANY MILES ARE ON THE BIKE AND WHAT HAS BEEN SERVICED? The mileage on a bike can be used as a very rough gauge to determine where it is at in its life however nowadays motorcycles are designed to perform well and not require a great deal of service work even with high mileage. How well the owner has taken care of the bike, the type of riding they did, and the conditions in which it was stored are all better factors for assessing where it is at in its life cycle. Street bikes typically require service after predetermined mileage intervals established by the motorcycle manufacturer. These services may include valve clearance checks, oil and filter changes, and clutch maintenance. This question will help you gauge when and how much upcoming service work may be required. In most cases street bike engines will last a long time and not require much internal engine work if the engine is routinely serviced and basic maintenance is performed. By familiarizing yourself with some of the routine maintenance tasks for the make and model you are interested in you can gauge the frequency and scope of work which is considered routine maintenance and compare this to what the seller tells you. Keep in mind if you are looking at bikes that have been raced or are of the single cylinder variety more maintenance may be required to keep them in top shape. LET THE ENGINE WARM UP & LISTEN TO IT IDLE Allow the engine to come up to operating temperature, this usually takes a few minutes of idling. Most bike are equipped with a coolant temperature gauge which you can reference to see how warm the engine is. Listen as the engine runs for how well the bike idles. The bike should have a nice consistent idle and the motor shouldn’t be hunting or surging. Assuming the bike is carbureted and does not idle, it is likely that the carburetor needs servicing or something is out of adjustment. If the bike is fuel injected and does not idle, there could be an issue with the fuel map, pump, or injector. SHIFT THROUGH ALL THE GEARS Feel with your foot how easily the bike shifts into the next gear. You should be able to feel if the gears kick back out or do not engage easily. If the bike jumps out of gear or does not shift well, there could be problems with the gearbox. Pay special attention to the shift from 1st to 2nd gear since this is the shift that requires the biggest stroke to engage (since neutral is between them) and usually wears out first. Typical problems may include rounded gear dogs, bent shift forks, or worn shift forks. Remember if any of these problems exist you will have to split the crankcases to remedy the problem (unless the engine utilizes a cassette style gearbox or has a separate transmission). Be sure to shift through all the gears at least a few times to make sure any problems that arise are repeatable and predictable. This will help rule out any user error where the rider did not shift fully. If you like the tips shared thus far and want to learn more about navigating the slippery slopes of buying a used bike, I would encourage you to download the free guide you need, whether it is dirt or pavement. The guides come in the form of a downloadable PDF, ready to be printed and kept forever. The Buyer’s Guides also include a checklist that you can bring along and reference as you proceed through all the steps of buying a used bike. The checklist is incredibly useful when it comes to looking over the bike and inspecting individual components. I know my adrenaline goes wild when picking up a new bike and I run the risk of skipping over one or two important things, so the checklist will ensure you do a thorough job. Just click the link below to go to the downloads! Grab Your Free Used Dirt Bike or Motorcycle Buying Guide Do you have any tips that I left out of the guides? If so, post them in the comments section so everyone can benefit from your experiences! Moto Mind - Empowering and Educating Riders from Garage to Trail P.S. If you haven't subscribed to my blog yet be sure to click the "Follow this Blog" button at the right of the page!  

Paul Olesen

Paul Olesen

 

Must Watch Motorcycle Films!

Must Watch Motorcycle Films! With the recent release of “On Any Sunday, The Next Chapter” and “Moto 6” I thought now would be a good time to introduce you all to a few motorcycle films that had a big influence on me as I was getting into this glorious sport. First I want to introduce you to “One Man’s Dream” which documents John Britten’s life and his effort to compete in world class road racing. Britten designed and built his own engine and racing bike with the help of his friends in New Zealand. The bikes were successfully raced all over the world up until the point when Britten became sick and passed away. The Britten motorcycle was on its way to becoming a production bike. The film does a great job documenting the triumphs and failures of the Britten team and will instantly have you hooked as you get a front row seat to the design, manufacturing techniques, and testing stages of the bike not often seen first hand! http://youtu.be/m9N1gfLQ--k If you enjoy the documentary I would recommend reading the book “John Britten” by Tim Hanna which chronicles John’s journey in a much more detailed way. While the movie depicts John as a national hero the book reveals some of John’s quirky traits, business dealings, and definitely paints a different picture about him than what you see in the film. The next film I want to introduce you to is “Love, Speed, and Loss”. This film documents Kim Newcombe’s journey to 1970’s road racing excellence. Kim is one of my role models and was a true outside-the-box thinker. Kim’s ability to mate a Konig four cylinder 500cc two-stroke outboard engine to a road racing chassis lead to his success and renown in the industry. Kim tragically passed away much too early and his full potential may never have been reached. Click Here to Watch "Love, Speed, and Loss" for Free on NZ Television. Most of you have probably heard of “World’s Fastest Indian” by now, but it is still an awesome film and worth a mention. Follow along with Burt Munroe as he sets out for Bonneville from New Zealand in an effort to set new land speed records. Burt’s “never give up” attitude and DIY mentality will instantly have you hooked as he tries to conquer records. “TT3D” - For those of you that aren’t familiar with real road racing this is a must watch! This documentary features Guy Martin, a British road racer and truck mechanic, who tackles the Isle of Man TT course every year in search of victory. With racing occurring primarily in Ireland this is one of the oldest and most dangerous forms of road racing and definitely worth checking out. “On Any Sunday” - I urge you to revisit a classic before or after watching the new release of “The Next Chapter”. This film is an all around great documentary for motorcycle enthusiasts everywhere. Click Here to Watch "On Any Sunday" for Free on Hulu I hope you guys enjoy my favorite motorcycle films as much as I do. If you have more awesome films you are addicted to that I didn’t mention leave a comment, drop a link, and share them with us! Moto Mind - Empowering and Educating Riders From Garage to Trail

Paul Olesen

Paul Olesen

 

The Top 5 Specialty Tools

The Top 5 Specialty Tools Today I wanted to start a discussion about the top specialty tools that every home mechanic should have in their shop or garage. I picked out my top five most important specialty tools and encourage you to add your favorites to the list by leaving a comment. The top five I have selected are critical for engine building and in my opinion the job cannot be done right without them. Torque Wrenches Believe it or not, every nut and bolt on your machine has a torque specification associated with it so that you do not run the risk of over tightening, damaging the fastener, or leaving something too loose. Even simple things, like the bolts holding your plastics on and your seat down, have torque values that you should aim to follow. While you might not get into trouble if you overlook using a torque wrench on these fasteners, I consider everything in the engine torque wrench territory. In order to build a good sound engine it is critical to follow the manufacturer's suggested torque specifications for all the fasteners and use a good quality torque wrench. On a four-stroke engine I would say the single most important thing to torque properly is the cylinder head nuts or bolts, depending on the model you have. If you over tighten it is very possible that you could strip something whether it be the nut, the bolt, or the crankcase threads. Ultimately if you overlook it or do it incorrectly, you have created additional work for yourself and taken a step backwards. Now let's assume you under-tighten the cylinder head. This won't result in a favorable outcome either. Your cylinder head gasket and base gasket both require a certain amount of pressure to compress them properly so that they seal. If you under-tighten your cylinder head the gaskets may not seal correctly and you may end up with coolant in your combustion chamber, coolant leaking out around the cylinder head, a cooling system that blows coolant due to the combustion pressure pushing it out, or oil leaks around the base gasket. In other words- bad news for a healthy engine. Usually the range of torques you will need to cover will require you to pick up a couple different wrenches. Right now I've got a small one that goes from 30-150in lbs for the delicate stuff and a larger wrench that goes from 20-100ft lbs. As for what brand is the best, everyone seems to have their favorite, but I personally like the wrenches CDI offers. CDI is a branch-off company of Snap-On and they offer great quality at less cost. I paid around $100 a piece for my wrenches, which came with all the necessary calibration paperwork I like to see. Flywheel Puller If you have to split crankcase you will have to remove the flywheel. I have heard stories and seen video footage of folks beating off their flywheels, but I definitely would not recommend this tactic. Picking up a flywheel puller for your specific model so you can do the job right is a much better option. The pullers are fairly cheap, easy to use, and make the job extremely easy. Strap Wrench The strap wrench is a great versatile tool. My favorite spot to use it is on the flywheel when I'm removing the flywheel nut. In order to remove the flywheel nut you will need to secure the crankshaft in some way. A lot of people will lock the crankshaft from the clutch side so they can remove the flywheel nut, but in my opinion this is not the best practice. If you lock the crankshaft on the clutch side and apply torque to the flywheel side, the crank will tend to twist around the crankpin. This may not be a huge problem when loosening the nut, but when you reinstall and torque the nut you run the risk of twisting the crankshaft. If you do end up twisting the crank you can expect expedited engine wear, excessive vibration, and main bearings that will not last long. Again, not good news for a healthy engine. Clutch Basket/Sprocket Holder The clutch basket holder locking pliers are truly the only answer for properly disassembling and assembling clutches. In the past I have seen screwdrivers jammed into the hub to keep them stationary while trying to tighten or untighten the nut. This sort of thing typically ends with damaged clutch parts, meaning more cost to you in the long run. The clutch basket holder locking pliers are great because they can be adapted for pretty much any size clutch hub and provide a solid means to retain the hub while fastening the nut. The pliers are fairly inexpensive at around $30 and some even double as sprocket holding pliers. Crankcase Splitter Splitting crankcases should be a delicate procedure, especially if the crank is to be reused, and having a crankcase splitting tool on hand makes the job a lot easier. I have seen videos of people beating on the end of the crank to push the cases out, but I assure you this is not the right way to do it and may put the trueness of the crank in serious jeopardy. The case splitter is a must-have and provides a way to evenly and gently separate the cases. Along with the other tools listed, the crankcase splitter is relatively cheap and will pay you back handsomely by helping you perform a top quality trouble-free build. I hope you guys agree with my top five specialty tool picks. Leave a comment with your favorite tools and why! Moto Mind - Empowering and Educating Riders from Garage to Trail

Paul Olesen

Paul Olesen

 

Who Keeps Track? - Ride Logging

Do You Keep Track? How many of you regularly keep track of the number of hours or miles that have accumulated on your engine since the last time you performed any type of service on it? How helpful would it be if you had a designated place to log any riding, maintenance, and suspension tweaks? Between riding and maintenance there is an awful lot of stuff to keep track of. The last thing I want to do is complicate the matter any further by having to try and remember in my head when the last time I did some work on the bike was. So what is the best way to keep track? Having a simple ride log/service sheet is a great way to keep track of your machine’s maintenance and stay ahead of any potential problems. Another awesome device to pick up for your machine is an hour meter. Hour meters are great since they only record actual engine running time, which gives you a more realistic time value than estimating how long your engine ran while you were out on your ride. I wanted to share with you the log I use to keep track of the time I put on my bikes. Click this link to download a free copy. I have set up three versions, one for Excel users, one for Google Docs users, and a PDF that can be printed for the folks that like to document their riding on paper.   Shown below is an example of the log I keep for my YZ250. The log is simple to use and helps document basic settings, maintenance, and engine run time. I like to keep track of location and weather conditions so I can document any variation in engine performance. This is particularly useful for carbureted machines since jetting is dependent on temperature and atmospheric conditions. Once you start to build a database of information you will start to notice trends that emerge based on where you are riding and the temperature. These trends will help you determine the proper jetting for given conditions more quickly and save you a large amount time in the long run. Keeping track of any maintenance you do on the bike along with the number of hours on the engine is a no brainer. Not only will this Ride Log help you determine when certain services are coming up, it will be a major confidence boost to a potential buyer concerning your maintenance of the bike if you ever decide to sell, and ultimately help you retain a good resale value. The suspension column I will use occasionally if I make a minor tweak, however the bulk of my suspension documentation goes into a suspension log. I added this column for those of you who do not change your suspension too often. I am going to discuss suspension logging with all of you coming up soon so stay tuned. I hope that you find the rundown of the riding log beneficial and that you decide to start keeping track of your riding to improve your maintenance practices! Keep in mind I tailored this to as many of you as I could. If you want to customize it for your specific discipline, feel free. Once you get into the habit of keeping track of these things you will end up taking better care of your machine and ultimately save yourself a huge chunk of time and money in the long run. Moto Mind - Empowering and Educating Riders from Garage to Trail If you'd like to follow my blog, click the "follow this blog" button in the upper right. I'd love to have you.

Paul Olesen

Paul Olesen

 

Leak It Down

Leak It Down What is a sure fire way to determine if your two-stroke engine has any unwanted air leaks? The leaks I’m referring to could be coming from crank seals, cylinder head gasket, base gasket, the spark plug hole, power valve mechanism, intake manifold, or exhaust manifold. Regardless of where these air leaks originate, they affect the performance of your engine, may make the engine difficult to tune, and should not be considered normal. Performing a leak down test is the best method for determining if and where air leaks are coming from. A leak down test is fairly simple to perform and can provide tremendous amounts of information about the health of an engine. I typically like to perform a leak down test on an engine if I’m having trouble jetting the engine consistently, if I’ve bought a used bike with a suspect past history, or when I’m finishing up assembling a new engine. The biggest mistake I see a lot of people make is when they rebuild an engine with new parts and skip the leak down test. I cannot count the number of times where I have rebuilt an engine with new parts and then performed a leak down test to find a gasket that was not sealing properly or another part that was causing a problem. The leak down test is imperative and ultimately becomes a form of cheap insurance against the time and money that has gone into the build. How exactly does a leak down test work? A leak down test works by pressurizing the crankcase cavity and cylinder. A plug is inserted into the intake manifold and another plug or block off plate is used on the exhaust to create an airtight cavity. A small air pump is used to pressurize the cavity to 5psi and the pressure is monitored in the cavity for around five minutes. If the pressure gauge holds steady at 5psi over the course of five minutes the engine is air tight and has passed the test. If the pressure ends up dropping over the five minute period, then there is a leak somewhere in the system which must be found and fixed. Although performing the leak down test is fairly simple, setting it up may be a little more difficult. I often find I need to make special adapters and block off plates dependent on each engine. If you have a reed valve engine, I like to install the reed valve and intake manifold. Then I make a plug which is the size of the carb/throttle body OD on the intake manifold side and slide that homemade plug into the intake manifold boot. Depending on your exhaust manifold there are two options for blocking off the manifold. First, it may be possible to find a rubber plug to plug-up the manifold directly. Most of these rubber plugs will be the expandable type and can sometimes be found at building supply stores like the Home Depot. Second, use the manifold as a template to make a plate, which then you can bolt in the manifold’s place. A steady helping of grease can be used to seal the block off plate to the cylinder. Pictured below is how I like to make my intake manifold plugs. I use a simple schrader valve and tap a fitting into the plug to accept the pressure/vacuum gauge. If you are going the route of the block off plate, simply use your exhaust manifold as a template and cut out a flat plate. After you've made all your parts the assembly should look something like this. I like to use a bicycle pump or a Mighty Vac to pressurize the crankcase cavity as it allows precise controllable pressurization. Do not attempt to use an air compressor since the pressure rises quickly and you run the risk of blowing the seals out. Fixing blown seals can be an expensive and time consuming affair. Once your setup is complete, pressurize the cavity to 5psi and start timing. If the pressure is lost quickly there is a large leak in the system and now you need to find it. I like to use a squirt bottle with soapy water to hunt for air leaks. It is also possible to hear the audible hissing sound from the leaks, which will point you in the right direction. Once you identify a leak you will have to determine what is causing it and remedy that problem before trying the leak down test again. This part of the process can be frustrating and time consuming, but it is definitely worthwhile. Be sure to spray your block off plate and manifold plug you made for leaks, sometimes these homemade parts can be part of the problem. If you’re able to hold 5psi for 5 minutes you’re golden. Sometimes this standard is not always achievable, and when that happens I am comfortable settling for a 1 psi drop over five minutes. Even with brand new parts I am not always able to maintain 5psi and believe this is due to parasitic leakage past some of the seals or gaskets. In my opinion, anything more than a 1psi drop means you should still be chasing that leak. I want to make a point of passing on some additional info I have heard over the years for the sake of completeness of this article. Other builders I have worked with will recommend testing vacuum for five minutes at 10in Hg (equivalent to 5psi of pressure) as well which will test the seals under vacuum. I have yet to find a seal that has passed under pressure but not under vacuum so I wouldn’t fret too much if you don’t have a means to pull vacuum when testing. If anyone out there has encountered this scenario I would appreciate your input. Good luck with your leak testing and I hope you find this article useful! Feel free to post any questions or comments you may have. There are numerous methods out there, however this method is what I use and have had the best luck with. Moto Mind - Empowering and Educating Riders from Garage to Trail If you'd like to follow my blog, click the "follow this blog" button in the upper right. I'd love to have you.

Paul Olesen

Paul Olesen

 

From Rust Bucket to Beauty Queen

From Rust Bucket to Beauty Queen This week I thought I’d switch gears and share with you the restoration of my 1975 Kawasaki H2. When it comes to the handful of bikes I have owned, this bike was the one where I would be completely heartbroken if something happened to it. Unfortunately that was just the case. My love affair with two-stroke bikes started while in college and the Kawasaki H2 happened to be the king in this arena, it fascinated me. Naturally I had to get my hands on one, but I couldn’t afford a running or restored one. So it turned out I needed a project! On a Wednesday night in the spring of 2008 I was perusing craigslist, using one of the national search engines, and found a pair of 1975 H2s in Dallas. Instead of dutifully studying for an exam I had on Friday, I got to thinking about how I could feasibly get these bikes over the weekend. Thursday rolled around and I was still mulling things over in my head. One of my girl friends came around that night to study for an exam we had on Friday and I mentioned to her how I wanted to get the bikes. She suggested we leave that evening and go pick them up. She had a commitment on Sunday but if we left almost immediately we could make it back in time. I wasn’t completely sure if she was serious, but I found out soon enough that she was dead serious. So we set off for Dallas and I got a pair of basket case H2s. When I got to Dallas I found that the bikes were in a worse shape than I had suspected, but I bought them anyway. Once I got back to Minneapolis, my friend and I promptly submitted our doctor’s notes so that we could make up the exam. Along with finishing up my studies for the year I got to work on the bike. Here the bikes are shortly after I got them home The restoration has started! Parts got sand blasted Covers got polished It took awhile but I was able to replicate the paint scheme pretty well using my homemade paint booth. I carefully rebuilt my engine Eventually after a lot of care, some head scratching (mostly due to the old wiring harness), and an awful lot of time I got the bike together and running. As I mentioned at the beginning of this post, this bike was the bike I would lose my mind over if something happened to it. Unfortunately the beauty was short lived. One fatefully hot summer day in July the bike tipped over and fell. Despite having the bike on its center stand, it still sank into the gooey tarmac and dented the freshly painted gas tank. Needless to say I was devastated. One GP bike build and three years later, I finally got around to repainting the body work, making new exhausts pipes, reshaping the cylinder heads, adding reed valves to the engine, getting rid of 2lbs of brake rotor, and adding a decent caliper and master cylinder. Now this bike, once a rust bucket, is even better and more beautiful than before. It’s hands down one of my favorite bikes to ride. Moto Mind - Empowering and Educating Riders from Garage to Trail If you'd like to follow my blog, click the "follow this blog" button in the upper right. I'd love to have you.

Paul Olesen

Paul Olesen

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