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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.

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Are Project Bikes Even Worth It?

Whenever purchasing a used dirt bike, no matter how well inspected, there is always an element of chance involved. The possibility of an engine failure is what worries everyone the most and is a costly disaster to deal with. For those mechanically inclined, seeking a blown up bike can be alluring because it allows the new owner a fresh start. While this may seem like an ideal situation how often does it financially make sense and how do you decide to make the purchase? At DIY Moto Fix we just picked up a 2006 Honda CRF250R “Project” over the weekend, and I want to share the financial reasoning that went into the purchase as well as discuss the critical inspections we made which led me to pull the trigger. Over the next several months we’ll see if I made a good decision! The criteria I intend on using to determine if my purchase was justified or not will depend on a couple things. First, if I sell the bike will I net more money than I have into it, or at the least, break even? Second, could I have spent an equivalent amount of money elsewhere and gotten a bike that has a freshly rebuilt engine, which to me, equates to a machine that will provide countless hours of trouble-free riding? The bike will also be the subject of several blog posts and perhaps videos. However, these uses will not be factored into the valuation of the decision. No corners will be cut throughout the rebuild, and the end result will be a robust bike that I would be proud to keep, should I choose to. That said, let’s take a look at what I picked up! The Bike I found the bike listed on Craigslist for $1000. There wasn’t much detail behind the ad, and it consisted of a couple of sentences. In summary, the ad basically said everything was there, a new crankshaft and main bearings were included as well as a new top end. A half dozen pictures were presented and the engine was neatly laid out. I contacted the seller and inquired if any engine components were missing or needed replacement. I was reassured the only things missing were the valve keepers! While it would be great to think the engine could easily be reassembled, I had my doubts. I needed to investigate in person. Preparation If you’re ever in a situation where you need to collect an engine in pieces, don’t rush and forget to come prepared. Some engine components shouldn’t get mixed around or interchanged and it’s incredibly helpful to keep the hardware separated by subsystems. Here’s a list of the storage aids I brought with: Sharpie marker Ziplock bags Boxes Plastic part bins The Real Story When I arrived, I was greeted by an avid rider who was friendly and had four seemingly well-kept bikes in his garage plus a bunch of moto-related parts, not a bad start. He showed me the 250R he was selling and I began my inspections. Inspections In most cases the engine internals aren’t accessible when looking at used bikes for sale, so as funny as it may sound, it can be really easy to get caught up in the excitement of the potential sale and forget to look at a lot of critical parts. Each major engine component that gets overlooked can be a several hundred dollar mistake and make or break the profitability of the purchase. I want to cover the engine internals I carefully inspect to estimate the cost of the rebuild. VIN Number I’m a practical person and highly recommend ensuring the VIN number is unmolested and the seller’s “sale story” remains consistent throughout the sale. Don’t bother inspecting anything else if the VIN number has been tampered with. On some bikes, such as this one, cable chafing wore through part of the VIN number. This type of wear is easily discernible from intentional tampering. Crankcases Crankcases are one of the most expensive parts on an engine to replace, so look carefully for cracks and other damage. Scrutinize bearing bores, seal bores, threaded holes, cam chain guide slots, gearbox features, and mating surfaces. In this particular case, both the left and right case halves were damaged. I’ve got a lot of work ahead of me to try and bring these back. We’ll discuss welding crankcases in an upcoming post! Crankshaft Check the crankshaft to ensure it is at the very least serviceable. Look for surface damage, worn or broken gear teeth, and pitting. I recommend always assuming the crankshaft will require a rebuild even if it feels okay. Fortunately for me, this bike came with a new Wiseco crank assembly. Bearings All the engine bearings should be checked for notchiness. Any bearings that are gritty or bind when rotated should be replaced. For this particular engine, I’m planning on replacing them all. Conrod I recommend installing a new rod in conjunction with servicing the crankshaft. However, if you’re considering using the crank assembly, inspect the rod small end and feel how the big end rotates. Look for pitting and signs of distress in the small end. Notchiness in the big end warrants further investigation. Cylinder Inspect the cylinder walls for damage. Any defects you can catch your fingernail in should be cause for concern. The cylinder that came with this engine will either be replated or replaced. Piston/Rings The condition of the piston and rings can help determine what may have led the engine to be sold in pieces, however, reusing it isn’t something I’d recommend. Get in the habit of automatically budgeting for a new piston assembly anytime you come across a project bike. Cylinder Head The cylinder head is an expensive assembly to replace. While you always want it to be okay, I’ve found that by the time the bike reaches “project” status many of the internals, including the cylinder head, are in need of major TLC. Occasionally the valve seats can provide insight, however, I prefer to look at the valves themselves. Inspect the combustion chamber, head gasket sealing surface, and threaded holes in the cylinder head. Stripped fastener holes in the cylinder head can be very challenging to fix. On this engine, the valve seats will need to be recut or replaced, at a minimum. Valves Take a look at the valve faces for signs of recession and damage. Severely worn valves will be visible to the naked eye. This is the case with my new acquisition. Camshaft Inspect the cam lobes and any associated bearings for damage. Any pitting present on the cam lobes will warrant replacement. I’ll be installing a new cam in this engine. Transmission The gearbox shafts and gears should be inspected carefully for damage. On machines that don’t shift well and pop out of gear, damage to at least two mating gears will preside. Look at the gear dogs for excessive rounding as well as the mating slot. On this 250R the gearbox is in great shape. Clutch The clutch is an easy component to inspect visually. Look for basket and hub grooving which signifies a worn out clutch. In my case, this was easy to spot. Bike Inspections I’m not going to deep dive into the bike inspections since we’ve discussed this in a previous post and put together a comprehensive guide on the subject, which you can find here. In this particular situation, based on the amount of distress the radiators displayed I have to assume they will need to be replaced. The rest of the bike was in okay shape and luckily for me, the seller had some spare plastics, spare seat, and new tank plastics, which helped sweeten the pot. Rebuild Estimate Replacement parts for different makes and models vary, but I tend to make rough estimates based on the table shown below. The table is presented in a la carte style so cost estimates can be determined depending on what components must be replaced. The next table details the components I’m expecting to replace on the Honda. In this particular case, I’m estimating I’ll have $1630 into the resurrection of the bike and engine. I bought the bike for $800, so I’ll have a total of $2430 into the machine if my estimate is correct. Keep in mind this excludes monetary consideration for my labor. Since I’m going to use the bike for multiple projects, accurately tracking my labor will be challenging. If you’re looking to turn a profit fixing project bikes though, it’s essential to have a handle on the labor associated with each project. Resale Value I did a quick search on Craigslist to see what 2004-2007 Honda CRF250R’s were going for. I found a smattering of list prices and reasoned that I could sell this bike for at least $2000. Now, going by the numbers that put me out $430, again excluding labor. Was it worth it?   As you can see from a financial standpoint this project probably wasn’t worth taking on, or was it? Apart from picking up a broken low-value machine and then completely rebuilding it, is there any other way to pick up a used bike that undergoes transformation and starts its life in your hands with a completely rebuilt engine? I highly value understanding the condition of my machines before I entrust them to carry me at high speeds past trees or over jumps so assessing the heart of the machine whenever practical is valuable to me. I also get incredible satisfaction from working in my shop and resurrecting a machine that may have otherwise been slated for the parts section of eBay. What about you? What is your take on project bikes? If you’re looking to expand your arsenal of skills when it comes to wrenching so you can take on more challenging projects, take a look at our two and four-stroke dirt bike engine building handbooks! The dirt bike engine building handbooks are nearly 300 pages apiece and share a wealth of knowledge you won’t find in your service manual when it comes time to rebuild your engine. Check them out on our website or on Amazon .   Thanks for reading and have a great week! -Paul 

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

 

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

 

How Do You Keep Track of Where Bolts Go During a Rebuild?

Alright guys, this week I just want to share a short and simple tip with you on how to stay more organized during an engine build.   When it comes to major engine maintenance or repairs, usually the engine covers have to come off or the crankcases must be split. The covers and cases are almost always retained using different length bolts. The repercussions of installing the bolts in the wrong order upon reassembly can be very damaging. This is especially true if you install a bolt that is too short for its location and only a couple of threads engage, ultimately stripping the threads when you tighten the bolt.   So what’s an easy way to keep track of cover or case bolts that are arranged in a pattern of different lengths?   My favorite way to organize these bolts is to take a thin piece of cardboard (think cereal box thickness) and then slit the approximate bolt pattern into the cardboard so that the bolts cannot get mixed up. A picture is worth a thousand words so check out the one below. You need not be an artist to apply this tip, simply slit the pattern, add a couple reference points and you’re done!     Do you have any organizational tips you’d like to share? Leave a comment below because I'd love to hear about them!   If you are looking for more helpful tips and engine building info, feel free to check out my book, The Four Stroke Dirt Bike Engine Building Handbook. You’ll find 301 pages filled with crucial and down-to-earth four-stroke engine building knowledge. You've got one more week left to use the offer code tt2016 and receive 15% off your order!   Paul

Paul Olesen

Paul Olesen

 

How Much Damage Can An Improperly Cared For Air Filter Cause?

I thought this week it would be a good idea to share with you an example of what can happen when dirt gets passed an engine's air filter. This will be a short post, but a picture is worth a thousand words. In my next post I’ll go into detail on how to properly care for your air filter to help ensure that this never happens to you.   The series of photos below shows a sad case where dirt has found its way into the engine and wreaked havoc. The photos are all from the KX250F I bought on the cheap with the sole intention of rebuilding the engine and documenting the process for my book, The Four Stroke Dirt Bike Engine Building Handbook. Honestly, I couldn’t have bought a better bike for the project, nearly everything on the bike was worn out or screwed up from the previous owner.   Here is how the air filter and airbox looked prior to disassembly.
  Here is the back side of the air filter. The filter was completely dry. There was no grease on the sealing face of the filter or the airbox flange. In this particular case, dirt could have got into the engine through the filter or between the filter and sealing flange. The amount of dried mud in the airbox and on the bike also makes me suspicious that muddy water got into the engine instead of just dirt. I honestly can’t say for certain.     The airbox itself was also extremely dirty.     Once the engine was disassembled I carefully examined the piston assembly and cylinder bore. At first, I could not get any of the rings to move freely. Only after I had pounded a pick between the ring ends of the compression ring was I able to get the compression ring off. As I removed the compression ring, a load of sand came with it.   This photo of the compression ring doesn’t do the situation justice. Some of the dirt was actually removed from the ring as I handled it.
  Here is a close up of the compression ring. Note all the grit!  
  The oil rings didn’t fair any better, were just as stuck, and had a lot of dirt on them.  
  Here you can see dirt inside the ring grooves and at the edges.  
  Here is dirt I rubbed off the oil rings.     Miraculously (and fortunately for me) whether the engine sucked in dirty air or water, it happened quickly and stuck the rings to the piston so they could no longer seal correctly, and the engine subsequently lost compression and power in a hurry. This speculation is based on the fact that the cylinder bore showed no signs of excessive wear or damage and it measured well within the service limits. This is an outcome I never though possible and is hard to believe.   I hope you enjoyed this brief write up on the damage that can result from ingesting dirt, whether from abnormal circumstances such as dropping a running engine into a mud hole or simply neglecting to take care of the air filter when running the engine in dusty conditions. In my next post I’ll show you how to care for and install your filters so these problems don’t happen to you! Questions or comments are always welcome and I enjoy hearing from you all!   -Paul
https://www.diymotofix.com/   If you like my blog, click the "Follow this blog" button in the upper right. You must be registered to do this.

Paul Olesen

Paul Olesen

 

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

 

Help! - Bike Only Starts When Pushed

Today I want to talk about a situation I hear all too often. Someone’s bike, whether it be a two-stroke or four-stroke, only starts when it is pushed.

Before I discuss potential causes for this scenario, take a moment to think through the situation yourself. What mechanical factors would result in either a two-stroke or four-stroke only starting when it is bump started?

In either case, the reason the engine is able to start when it is push started is because it is able to build more compression than it otherwise could when it is kicked or the electric starter is engaged. More compression is achievable because the cranking RPM is higher than what’s possible with the aforementioned starting methods. With a higher cranking RPM for a four-stroke, more air will fill the cylinder on the intake stroke, and for a two-stroke the scavenging process will be improved. With this being the case we must look at reasons why the engine is struggling to build compression in the first place.

Starting problems specific to four-strokes:
1. Valve seat recession - When a valve seat wears out and recedes, the valve moves up towards the camshaft. This leads to diminished valve clearances and if left to run its course, the valve and shim will bottom on the camshaft’s base circle. This can prevent the valve from seating and make the engine hard to start. 2. The valve is bent - A valve with a serious bow to it may get jammed up inside the guide and not return all the way back to its seat. Bent valves typically result from an over-revved engine where the valves contact the piston. Valves can also bend to a lesser extent if they were mated to valve seats that were not cut concentrically to the guides, or they were paired with worn seats.

3. The valve stuck in the guide - This is usually due to the engine overheating. When the engine overheated the clearance between the valve and guide diminished which caused metal to transfer from one part to the other, ultimately ruining the surface finish on one or both parts. Once this happens the valve may be prone to sticking in the guide until the engine warms up. 4. The valves and seats do not seal well - Worn valves and valve seats can compromise the seal between them. Valve and seat wear is a natural part of running an engine but can also be accelerated by ingesting dirty air.

Starting problems specific to two-strokes: 1. The reed valve is worn - Reed petals that don’t close all the way, are chipped, or bent will not allow sealing of the crankcase and efficient gas flow up from the crankcase into the cylinder.

2. An engine seal or gasket has failed - A two-stroke engine requires a well sealed crankcase and cylinder in order for it to scavenge gases efficiently. A worn crank seal, leaky base gasket, or problematic power valve seal can all make starting more difficult. Two and four-stroke problems: 1. The piston rings are worn - Worn piston rings will allow compressed gases to escape past them. 2. The head gasket or o-rings are leaking - Usually a leaking cylinder head will be accompanied by white smoke if coolant is being pushed into the combustion chamber, by coolant being blown out the radiator, or both.

I hope you found this rundown of potential problems useful for diagnosing bikes that like bump starting over a kick or the push of a button. Can you think of any other problems that would lead to lack of compression? If so, leave a comment and share them. If you liked this post and want more technical info, check out my book, The Four Stroke Dirt Bike Engine Building Handbook. In it you will find over 300 pages of technical knowledge to help you get off on the right foot when rebuilding!

- Paul
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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

 

What Spare Parts Do You Bring To The Track or Trail?

With warmer weather and the riding season around the corner for many of us, I wanted to cover a topic that can either make or break an event. Whether you’re competing in a racing series or traveling to the track or trail, let's talk about event preparedness. More specifically, what spare parts should you keep on hand? Plus, what methods do you use to keep your spares organized?

Honestly, I struggled with organization until I started working on this post. I had no method to my madness. Every time an event came up I’d do the same thing; throw a bunch of stuff in a box or the back of my van and head to the event. The sad part is I now realize this was a weakness of mine for quite some time, but didn’t do anything about it! Maybe you can relate?

I finally said enough is enough. I don’t throw my tools in a cardboard box when I go to a race, leaving what I bring to the fate of my memory. So why would I do that with the spare parts I bring?

I started solving this problem by compiling a spreadsheet detailing what spare parts I keep on hand for ice racing and hare scrambles. I realize that each discipline will differ and may have niche parts that should be kept. The goal here is not to definitively define what spares one should keep on hand, but to have a conversation and provide a resource that can be used to help people get set up based on their own needs.

Once I took inventory of everything I felt I wanted to bring to a race, I went to Menards and went hunting for the perfect organized storage bin/toolbox. Here’s what I ended up with:



Naturally, once I returned with the toolbox, my list grew and I probably need to go back for a bigger one. I intend to store a copy of the spreadsheet in the tote so I can keep tabs on inventory and know exactly what I have available.

Should I get another bike, this system is easily replicable and my plan is to get another organized toolbox that goes with it.

This system is how I went from being an unorganized “throw it in the van at the last minute” rider to a more relaxed well prepared rider. I’d love to hear how you handle event readiness, what you bring, and how you keep track of it. My hope is that by sharing our strategies we’ll save someone the misfortune of having a bad day at the track or trail. Perhaps I'll even end up with more things I need to add to my list.

-Paul

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Paul Olesen

Paul Olesen

 

What Do You Love and Hate about Today's Machines?

Today I want to shift gears, open the floor for discussion, and talk about the state of dirt biking as it relates to the bikes we buy, ride, and maintain. In my relatively short existence, a number of things have happened in the industry which has been interesting to see. A few examples, which are not by any means exhaustive of all that has gone on, include the emergence of the four-stroke power plant, electronic fuel injection, improved tire technology, electric bikes, and the development of air forks. On a more micro-level we’ve seen improvements to materials, new manufacturing processes, and coating processes which have allowed ever increasing performance. As a fellow rider and someone who has no bias or stake when it comes to manufacturers and product offerings, I’d like to hear your thoughts as they relate to today’s machines. My question to you is a simple one, are your needs as a consumer being met by today’s manufacturers and bikes?  What aspects of today’s machines do you love and what are pain points for you?  If you could do things your way, what would you change? Are there machine variants that aren’t being offered?  Leave a comment below that addresses these questions or share your historical perspective! I look forward to your responses. Thanks and have a great week!

- Paul
https://www.diymotofix.com/ 

Paul Olesen

Paul Olesen

 

Who Warms Up Their Engine Anyway?

Whenever I’m out and about either riding my motorcycle or participating in racing events occasionally I see things that just make me wonder “why”? One of those moments is when I see someone take a cold bike and fire it up for the first time and bang it off the rev limiter, start riding it immediately, or annoyingly continuously blip the throttle as if it will never idle on its own. These actions beg the question, “Why is it important to warm up an engine”? The answer lies in a simple explanation of science and mathematics. Before you quit reading because you may not have been an ace at math and science in high school, just give me a minute to break it down. It is actually really simple. The whole reason we need to let our engine warm up revolves around the concept of linear thermal expansion. Your engine is made up of a number of different materials. The piston is made from a certain type of aluminum alloy, the cylinder another type of aluminum alloy, the rings cast iron or steel, the valves if you have a four-stroke from steel, stainless, steel, or titanium, and the guides are made from yet another material. Once the engine is started these components begin to heat up from combustion and friction as they slide back and forth. None of these materials are exactly alike, and because of this they will expand when heated or contract when cooled at different rates. This interaction between material and change in temperature is predictable and linear. Now that we understand that engine components change dimensionally from when the motor is cold to when the motor is warm we can start to see the importance of warming up the engine. When a cold engine is first started the piston heats up and expands first. Heat is transferred from the piston to the rings and then to the cylinder wall. If we rev the engine and generate lots of combustion cycles and increase the frequency of friction too early the piston will grow much faster than the cylinder. If there is not adequate space between piston and cylinder to account for this growth the engine could suffer what is known as a cold seizure and you will have yourself a bad day. By allowing your engine to warm up before you start riding you allow all the components in the engine to slowly expand and stabilize. Once the engine is warm, changes in the engine part dimensions are less drastic and there is much less risk of damaging the engine. The picture below shows an engine which was limped home after the coolant started leaking out. As the engine lost its ability to cool down, things began to tighten up. You can see how the piston contacted the cylinder evenly around the bore and created the vertical scuff marks. Even though this engine didn’t completely seize, you can imagine the severity of scuffing would be much worse for an engine that would seize. So you are probably wondering, “how do I know when my engine has properly warmed up then?” and, “what exactly do I do to properly warm it up?” The procedure for warming up the engine is simple. 1. Start the engine using the choke if necessary 2. Once the idle comes up due to the choke turn the choke off 3. Allow the engine to idle with the choke off until the cooling system warms up and the engine comes up to temperature. Knowing when the engine is ready to ride is a bit subjective. As you begin to pay closer attention to your engine, you will begin to detect when it is ready to ride. Personally for water cooled engines I like to feel the radiator and use that as an indicator. I place my fingers on the side of the radiator where the coolant is returning from the cylinder head and lightly touch to get an idea of how warm the coolant is. I do this until the radiator is just getting uncomfortable to touch. This typically only takes a few minutes and after that I’m ready to start riding the bike. For air cooled engines my approach is much the same except I feel the cylinder and head to determine when I think the motor is warm enough to ride without causing any unnecessary wear or damage. Paul 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

 

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

 

Four Stroke Cylinder Head Reconditioning

It's time to open up a can of worms and talk about a hotly debated topic in the powersport community - four stroke cylinder head reconditioning best practices. I've perused the forums and had discussions with people about reconditioning four stroke cylinder heads and there appears to be a lot of mixed opinion and beliefs on what is right or wrong. I'm certainly not going to say my take on the subject is the only way, but I do want to share my opinion, explain the technical details, as well as touch on the machining process. The text below is out of my book, The Four Stroke Dirt Bike Engine Building Handbook, and details why cylinder heads should be reconditioned a certain way.  Whenever new valves are installed in a cylinder head, it is best practice to recut the valve seats since the valves and seats are mated parts, otherwise the new valves are very susceptible to premature wear when run in the old seats. If a major overhaul is being performed, there is a good chance that enough seat wear will have occurred during the engine’s life that the valve seats will need to be recut before new valves are installed. This may be news to you, so I want to provide an explanation of why this is necessary. 

The term concentricity is used to describe the relationship between the axis of two circular objects. When two objects are perfectly concentric, their axis match up precisely with one another. In the case of the cylinder head, the valve guide axis and the valve seat axis must be as close to perfectly concentric as possible and parallel to one another. Usually, guide to seat concentricity is kept around 0.001” (0.025mm) or even less for racing applications. This is achieved by the factory by using a manufacturing process where the valve guides are reamed first. Then the freshly reamed valve guide bore is used to center the valve seat cutter. Once centered, the valve seat is cut. This process is then repeated for all the valves and results in very good concentricity between the valve guides and valve seats. As the engine is run, the valve guides, valve seats, and valve faces will wear. The valve guides will wear from front to back in an oval shape at the top and bottom of the guides. In a cross sectioned view the valve guide will take on an hourglass shape. The guide will become oval as a result of thrust forces stemming from the way the camshaft contacts the lifter bucket or rocker arm. These forces are transmitted to the valves and cause the valves to thrust against the sides of the guides, eventually causing the guides to become oval shaped. Once the guides start to become oval shaped, the valve faces will no longer be as concentric to the valve seats as they originally were. When this happens the valves will start to slide against the seats, causing the seats and valve faces to wear. The valve seats will eventually become out of round and the sealing between the valve face and seat will suffer. Installing new valves into oval shaped guides and out of round seats will ensure that the new valves wear out very quickly!

To ensure the new valves being installed last as long as possible, the cylinder head’s seats and guides must be reconditioned once they are worn out. Complete cylinder head replacement is always an option, but I want to focus on freshening up the original head which is usually a more economical option, but comes with many more variables surrounding the quality of the job.

There are numerous services offered in the marketplace for valve seat cutting, however, not all valve seat cutting methods are equal in terms of quality. There are hand operated seat cutters, dedicated seat cutting machines, and a few other options to choose from. Selecting the correct seat cutting process and entrusting the work to a competent engine builder is very important. The valve seat cutting process should mimic the OEM process as closely as possible. A concentric valve seat will never be able to be cut without first servicing the valve guides. If the valve guides are out of round then they will either be reamed to a slightly larger size if they are not too oval in shape or they will be replaced. Once any issues with the valve guides are addressed and they are perfectly round from top to bottom, it will be possible to cut the valve seat. Ensuring the valve guide is perfectly round is extremely important since the valve seat cutter is centered off of the valve guide bore.

Cutting the valve seat concentrically to the guide requires a combination of skill and using modern machinery. The best valve seat cutting equipment in the world is worthless without a good experienced operator running it. There are two main factors which make cutting a seat concentric to the valve guide difficult. To start with, the valve seat cutter uses a pilot which locates in the valve guide. Since the valve stems are very small in diameter the pilots used to guide the seat cutters are also very small in diameter. A small diameter pilot shaft that centers the cutting tool can flex easily, which presents a real problem when cutting the seats. The next issue that arises when reconditioning seats is that often times the cutting tool will try to follow the path of the old valve seat which can make it hard to cut a concentric seat. Couple these factors together with slop within the machine, setup error, and operator error and you can see how quickly things can come out of alignment and you can end up with a poorly cut seat. In addition to seat concentricity, the depth the seat is cut to will influence valve spring pressure, shim sizes, and the compression ratio of the engine. All three of these variables will be reduced the deeper the seat is cut, which is not a good thing. The surface finish of the seat itself will influence how well the valve seals. A seat with chatter marks or other machining blemishes will not seal as effectively as a smooth seat. The valve seat width and the contact point between the seat and the valve face are also very important. Due to the complexities involved with cutting valve seats on modern four-stroke dirt bike engines, the job should not be left up to just anybody. There are numerous businesses which specialize in valve seat cutting which have both the right equipment and expertise to do the job correctly. I highly recommend spending some time researching and finding a reputable cylinder head machining company when it comes time to recondition your head. If the cylinder head must be shipped off in order to do business with a reputable company, the additional wait will be worthwhile. If you found this information helpful and would like more technical info on maintaining your four stroke engine, check out my book, The Four Stroke Dirt Bike Engine Building Handbook. Thanks for reading and happy wrenching! As always if you have comments or want to share your thoughts please leave a note below.

-Paul



Available at: 
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Paul Olesen

Paul Olesen

 

Three Easy Ways to Improve Engine Cooling

This month I want to discuss three easy ways to improve engine cooling for your dirt bike or ATV and explain why they are effective. As improvements are made to an engine that increase its power, the amount of heat the engine will create will also increase. Effectively removing heat from the engine and cooling it is very important as the power output of the engine goes up. The cooler an engine runs, the more power it can produce. There are three ways that the aftermarket attempts to improve the cooling system of a particular engine. 1. Increase flow through the cooling system. 2. Increase the cooling capacity of the radiators. 3. Increase the pressure of the cooling system. Let's dive in. 1. Increase flow through the cooling system
The flow through the cooling system can be increased by installing a water pump impeller designed to increase the flow rate of the coolant. The reason increasing the flow rate of coolant works is because the rate of heat transfer from the engine to the cooling system is directly proportional to the mass flow rate of coolant. This is thermodynamics jargon, but there are two key parts to consider. First, how much coolant is flowing, and second, at what speed the coolant is flowing. The more coolant that flows and the faster it flows will reduce the temperature difference between the point where the coolant enters into the engine and where it exits. This next part is not quite as intuitive. When the temperature difference between the inlet and outlet is reduced, the average coolant temperature is lowered. When the average coolant temperature is lowered the engine will run cooler. This is why fitting a water pump, which increases the flow of coolant through the engine, improves cooling. 2. Increase the cooling capacity of the radiators
Radiators consist of a series of tubes and fins which run from the top to the bottom of the radiator. These are often referred to as the radiator’s cores. As coolant enters the radiator it moves through the series of tubes and heat is transferred from the coolant to the fins. Air passes over the fins and heat is transferred from the fins to the air. This transfer of heat from coolant to air is how radiators reduce the temperature of the coolant. Coolant temperatures can be reduced by upgrading radiators in three ways, by increasing the frontal area of the radiators, by making the radiators thicker, or by using materials with better heat transfer properties for the cores. For all practical purposes, increasing the radiators’ frontal area and improving the core materials is rarely a viable option for dirt bike applications. This is because there is little room for the radiators to begin with and they are susceptible to damage, making the use of expensive core materials a risky affair. Unfortunately, both of these options are better improvements to make before resorting to increasing the thickness of the radiators. Increasing the thickness of a radiator is not as efficient of an improvement as increasing the frontal area of the radiator. In order for thicker radiators to cool more effectively than their stock counterparts, airflow past the radiators is key. When the thickness of a radiator is increased, air must travel a greater distance through the radiator before exiting. The speed the air is traveling plays a big role in determining how quickly the air heats up as it moves through the radiator. If the air is not traveling fast enough through the radiator, the air temperature will rise and equal the coolant temperature before reaching the end of the radiator. Once this happens, heat transfer stops and whatever portion of the radiator remains will not help with cooling. In order for a thicker radiator to be effective, air must flow quickly enough through it so that the exiting air temperature is at, or better yet, below the coolant temperature. In conclusion, benefits from adding thicker radiators will be more prominent in applications where speeds are relatively high. Whereas in applications where the bike is hardly moving, improved cooling may not be noticeable. 3. Increase the pressure of the cooling system
The last alteration to the cooling system that can be made is to install a high pressure radiator cap. As coolant temperature increases, pressure increases inside the cooling system. The radiator cap is designed to be the pressure release point in the cooling system in the event that too much pressure builds up. This can occur as a result of overheating or a blown head gasket for example. By designing the radiator cap to be the weak link in the system, other parts of the system, such as seals, don’t end up getting damaged from being over pressurized. The radiator cap features a plug and spring on its underside. The spring is designed to compress once a certain pressure is reached, at which point the plug will move upwards and uncover a pressure release hole where excess pressure will be vented.



The coolant’s boiling point and ability to conduct heat are necessary factors in understanding why a high pressure radiator cap can help improve engine cooling. Water alone boils at 212°F (100°C) while a 50/50 mix of water and antifreeze boils at 223°F (106.1C). Radiator cap pressure designations are usually advertised in bar, with most stock radiator caps designed to withstand pressures up to 1.1 bar (16psi). The more pressure a fluid is under, the more difficult it becomes for the fluid to vaporize, and the higher its boiling point becomes. When water is under 1.1 bar of pressure, the temperature water will boil at is 260°F (127°C) while a 50/50 antifreeze mix will boil at 271°F (133°C). By installing a radiator cap designed to withstand higher pressures, an additional increase in the coolant’s boiling point will be seen. High pressure caps are usually designed to withstand 1.3 bar (19psi) of pressure. This 0.2 bar (3psi) increase in pressure over the stock system will increase the boiling point of water or antifreeze by 8.7°F (4.83°C). This will then bring the boiling point of pure water or a 50/50 antifreeze mix to approximately 269°F (132°C) and 280°F (138°C) respectively. While this small temperature increase alone won’t do a lot for your engine, coupling a high pressure cap and using coolants with better heat transfer properties can do wonders. Antifreeze (ethylene glycol) alone is not an inherently good conductor of heat. In fact, pure antifreeze conducts heat about half as well as water, while a 50/50 mix of antifreeze and water conducts heat approximately three quarters as efficiently as pure water. This means a cooling system using a 50/50 mix of antifreeze would have to flow faster than a cooling system filled with pure distilled water in order to achieve the same cooling efficiency. What this means for you is significant cooling gains can be made by using distilled water and an additive called “Water Wetter” in place of an antifreeze-water mix. Water Wetter is an additive that improves water’s “wetting” abilities (another whole subject), adds corrosion resistance, and slightly increases the boiling point of water. A high pressure radiator cap in conjunction with distilled water and Water Wetter as the coolant is by far the best route to go for high performance applications where freezing is not an issue. For applications which must still be resistant to freezing, the antifreeze-water ratio can be altered in favor of mixtures incorporating more water than antifreeze so that the cooling efficiency of the mixture is improved. Just bear in mind the freezing point of the mixture as it is thinned with water will be reduced, so you will need to pay close attention to the environment you are operating in so that the coolant is never susceptible to freezing. A frozen coolant system can ruin an engine and makes for a very bad day! I hope you enjoyed this post on three easy ways to improve your engine’s cooling.  One more thing before I wrap up! April is Autism Awareness month, and here at DIY Moto Fix we couldn't be more excited to announce that we will be donating 15% of all profits made in April to AutismMX. If you haven't heard of AutismMX, this amazing non-profit brings Autism awareness to the motorcross community. Founder, Matthew Dalton, created this non-profit after finding that motorcross was an amazing way to connect with his autistic son. At DIY Moto Fix this non-profit also touches a chord with us. Our filmmaker and photographer, Kelsey Jorissen, loved dirt biking with her autistic brother throughout their childhood. The Autism MX Project focuses on four areas: Autism MX Day Camps are days for ASD kids and families to have the chance to ride AMX’s little dirt bikes and quads and enjoy the sport of motocross. Team Autism MX Sponsoring amateur MX racers, riders as well as sponsoring AMA pro racers. Through doing so, they are getting out the word on Autism Awareness to millions. AMX Puzzle Piece Apparel from shirts, graphics, goggles, to help stand out and support Autism Awareness. AMX Ride Days for Autism Awareness AMX celebrates Autism Awareness and is a fundraiser for The Autism MX Project. So for the entire month of April - if you buy a book, a video, even a poster - 15% of that purchase will go towards AutismMX and their amazing cause. Thanks for reading and have a great rest of your week!

Paul Olesen

Paul Olesen

 

Premix Once - Measure Twice

Premix Once - Measure Twice I cringe when I see someone guess at the proper amount of oil to mix with their fuel when filling up their two-stroke dirt bike, snowmobile, jet-ski, or even weed whip. Manufacturer’s spend an awful lot of time figuring out what the right amount of oil is for a given engine application so when I see someone add a splash here and a splash there and call it good it worries me. If you’re one of those folks maybe after reading this it will worry you too. Adding too little oil may lead to improper lubrication of the crank bearings, rings, piston, and rod bearings causing premature failure due to excessive wear and increased friction. You might think using less oil will save you a few dollars, will lead to more horsepower, or will keep your spark plug from fouling. Let me assure you that buying another quart or gallon of oil is much cheaper than having to replace an entire top and/or bottom end. Personally I have not come across a single study that proved less oil lead to more horsepower. I have ran oil mixtures as rich as 20:1 and have not had any problems with the bike fouling plugs. In my opinion, plug fouling occurs from poor combustion (possibly caused by combustion chamber shape, spark strength, or ignition timing) not the amount of oil in the mixture itself. Let’s consider the effects of having an oil mixture that continually varies each time the bike is filled with fuel. As an example let’s say that the bike and carburetor is set up to run at a fuel/oil ratio of 40:1. What happens if we get generous with the amount of oil we add when we fill the bike up? Let’s say after we finish filling we end up with a fuel/oil mixture that is 20:1. Now the bike has much more oil in the fuel mixture than there was originally. There is no question that the engine will be well lubricated, but will the engine perform better or worse? Assuming that no changes are made to the carburetor to account for the richer oil mixture, the engine will most likely run worse. The reason being the amount of fuel able to pass through the orifice of the main jet, pilot jet, and needle circuit is reduced due to dilution caused by more oil. This will cause the bike to run lean and may lead to problems! While you may think you are doing the engine a favor by giving it more lubrication, unless the carburetor is adjusted to compensate for this change, you are actually increasing the chances of doing damage to the engine by running it lean. On the flip side we could decide to take our engine that is set up to run a 40:1 fuel/oil mixture and use less oil. Let’s say we are down to the last quart of oil and need to get a couple bikes through a weekend of riding so we skimp and run the bikes at 80:1. In this case the opposite will happen. Since there is less oil in the fuel/oil mixture, more fuel will be able to flow through our carburetor circuits, thus causing the bike to run rich. A rich bike is much better than a lean bike, but what if there is no longer enough oil to adequately lubricate the engine? If there isn’t enough oil to lubricate the moving components within the engine, it is highly likely that engine components will wear faster, run hotter, and ultimately fail. My advice to you would be to take the extra five minutes every time you mix to measure out the amount of gas and oil precisely. That way each time you fill the bike up you are giving your engine the most consistent fuel/oil mixture possible. Taking the time to do this will lead to more consistent performance, maintenance intervals, and save you a lot of money on an avoidable rebuild. If you don’t already have an oil measuring container go out and pick one up for a couple bucks and throw it in with your riding supplies so you are never in the situation where you have to guess. Another tip I want to share with you is when you are at the gas station filling up your container with premium, let the first gallon of fuel go to your car or truck. By doing this you purge the gas pump’s hose of whatever blend was previously dispensed and ensure you are in fact getting premium for your toys. Once done filling and mixing, I like to label my gas jugs with the date I mixed them and with the fuel/oil mixture I mixed. Doing these simple things will help avoid confusion down the road and a keep your engine healthy. 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

 

DIY Piston Ring Compressor

Today I want to share a quick tip with those of you who are working on your own engines but just can’t justify buying a set of piston ring compressors. It’s entirely possible to make a perfectly good ring compressor from materials you can get at the hardware store. All you need is some plumber’s pipe hanging tape and a hose clamp that is sized according to your cylinder bore.

To construct a DIY ring compressor from plumber's pipe hanger tape you will need to determine the length of tape required. This is easily done using the following equation for calculating the circumference of a circle. Length of Tape Required = Piston Diameter x π (Pi) When the tape is wrapped around the piston tightly, the final length may need to be reduced slightly so that the ends don’t butt together. Once the tape has been cut to length, make sure whichever side of the tape will be contacting the rings is smooth and free of little plastic burrs that could catch the rings.

Simply lube up the tape, tighten down the hose clamp, and you are in business.



Do you have a tip that makes compressing rings easier or cheaper? If so, leave a comment below! - Paul

If you enjoyed this tip and want access to more like it, check out my book, The Four Stroke Dirt Bike Engine Building Handbook. On the fence about the book? Check out what other riders are saying: Thumper Talk Review

Available at: Amazon.com 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

 

The Top 6 Characteristics You Need To Have To Rebuild An Engine

I hope you’re all having a good fall and are getting excited for the holidays. It snowed for the first time this year here in Wisconsin and I’m getting eager for the lakes to freeze over so I can get out and ride the ice. I need to set aside a good 7 hours to stud my tires and set up my bike before that can happen though!   Today I want to talk about six characteristics that are necessary to have when one sets out to build an engine. I’ve detailed how to tackle many different jobs, but honestly that is only half the battle. If you’re in a rush or lack the desire to understand the reasons behind what you’re doing, you will make mistakes and miss out on important things. Listed below are the traits that I believe can help you take your build to the next level.   1. Being Detail Oriented
What’s worse than getting started on a build only to realize you didn’t buy an important replacement part? Focussing on the details of a project can feel tedious at times but can pay off in the grand scheme of things. Before I get started on a project I spend a hefty amount of time researching what parts I’m going to replace and where the best prices are. Also, I will have a solid idea of the sequences I’ll use for disassembly and assembly. Another good habit for the detail oriented is to take notes throughout the build, which you can use at a later date should the need arise. When you have an appreciation for all the small details that go into a build, it will make for a much smoother project.   2. Having Patience
Have you ever been in a rush to do something and after you’re done you realize if you had spent just a bit more time the project could have turned out much better? I was this way with so many of the things I did when I was younger, but have learned to slow down and be patient as I work. Engines don’t go together instantaneously and being patient throughout the process, especially when things aren’t going as planned, is very important. There is nothing worse than making a huge mistake because you’re in a rush. Imagine finishing a build and realizing you left an important part on the table, depending on where the part came from, you just bought yourself another few hours of work. Trying to skimp on time more often than not costs you more time in the long run. Have patience and enjoy the process.   3. Being Observant
Just about every mechanical thing is gleaming with a story, and that story only reveals itself if you know what to look for. An engine is no different. From the parting lines on a component left by the casting tooling used to create it to wear patterns on a piston, there are hundreds of observations that can be made while working on an engine. As you work, keep an eye out for subtle anomalies that may tell you why something failed or broke. For example, things like snail tracks across a gasket, raised edges on gasket surfaces, or covers that don’t sit flat on a table - these are all good indicators of why a particular part was leaking.   4. Being Curious
Perhaps more appropriately titled, “a desire to understand mechanical workings”. It is incredible how much can be learned about the engine just by studying how specific parts interact within it. An engine is composed of many different subsystems and they must all work in order for the engine to function. By looking at the various interactions of the parts within an engine, the condition of the parts and reasons for any failures can be more easily understood. The next time you build an engine, challenge yourself to learn how all the different subsystems of the engine work. Once you learn this, diagnosing problems and identifying all the faulty parts becomes much easier.   5. Being Meticulous
The necessity to be thorough and meticulous throughout a build cannot be overstated. Whether it be taking extra steps to inspect components, measuring new parts, or taking extra time to ensure the condition of surrounding subsystems are okay, having meticulous tendencies can pay off. As an example, on more than one occasion I’ve purchased new parts that have been mispackaged or out of spec. Had I not made the choice to carefully measure the problematic new parts, I could have ended up with an engine that was destined to fail. While it may take more time to be meticulous throughout a build, there is a lot at stake, both in terms of time and money, making it all the more important to ensure everything is done correctly.   6. Having Ambition
Building an engine can be hard, things can go south unexpectedly, and projects can easily stall. Being ambitious and having a can-do attitude is important to ensure the engine doesn’t sit half torn apart in the garage never to be completed. Until you tear into the engine, you never know what you might find. I’ve disassembled engines many times in the past only to find I need to replace a lot more parts than I had planned (this seems to be my luck when I shop for bikes on Craigslist as of late). This can be a huge downer, but keeping the end goal of getting back out and riding in mind and having the desire to push through any and all obstacles is a must.   Do you have any engine building characteristics you want to share? Leave a comment below and tell everyone what you think it takes to build a great engine!   For those of you that believe you possess the characteristics of a good engine builder, be sure to check out my book, The Four Stroke Dirt Bike Engine Building Handbook, to learn more about the how and why behind engine building. Whether you want to be taught about the relationships between all the various parts within an engine, you are in need of pointers on picking the right performance parts, or you would like to see examples of wear patterns found on engine components, my book is here to guide and help you throughout your build.   With the holidays coming up, I want to extend a special four day offer to you for the handbook and all the other products at DIY Moto Fix. Between November 27th and November 30th if you purchase anything from DIY Moto Fix you will save 30% on your order. If you’ve got a significant other trying to do some holiday shopping for you, be sure to send the site their way before Monday the 30th  
Save 30% and check out the book and other products by clicking this link: DIY Moto Fix

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

 

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

 

What Changes In Valve Shim Size Can Tell You About Your Engine

I hope you enjoyed my last post on ice tire studding! The season in my neck of the woods has been a bit short this year and I may be getting back to the dirt sooner rather than later. Nonetheless, Part II, which covers mounting ice tires is now up on my blog. You can view it here: Ice tire mounting.   In today's post I'm going to shift focus back to the engine and talk a little about valve technology. Valve technology and manufacturing techniques have changed substantially from the earlier days of engine development and I want to share with you some information about the current valve technology being implemented in your engines. I also want to discuss one way you can get a feel for how much life is left in your valves. Let’s get started.   The following excerpt is copied directly from my book, The Four Stroke Dirt Bike Engine Building Handbook. If you want to learn more helpful tips, which will bring your maintenance knowledge and engine building skills to the next level, I’d like to invite you to pick up a copy of my book by clicking here. Be sure to use the offer code tt2016 to get 15% off when ordering!   Alright, on to valves shim sizes.   The cylinder head assembly of most engines will wear out before it resorts to telling you it has had enough by catastrophically failing. Diagnosing these wear signs and knowing when it is time to replace components is the key to keeping the cylinder head assembly from failing. Due to the aggressive camshaft profiles, high compression ratios, and high RPMs required to make a lot of power, the valves and seats typically are the first parts to wear out within the cylinder head. Worn valves and seats will cause the engine to become difficult to start, have low compression, and have reduced power.     Modern valves found in dirt bike engines are made from either titanium or stainless steel alloys. Regardless of valve material, modern valve faces are either coated in a variety of anti-wear materials or hardened using various hardening processes. Common examples of trade names you might be familiar with include diamond like coatings (DLC) and black diamond coatings. These coatings are typically harder than the base material of the valve and help the valve resist wear, which occurs from ingesting dirty air and repeatedly contacting the valve seat. Coating and hardening processes are only present at the surface of the valve face. Depending on the type of valve and process used to harden it, the coating thickness can range from as little as 0.0001” (0.003mm) to around 0.003” (0.076mm). An easy way to visualize the thickness of the coating is to pluck a hair from your head and either measure it or feel it between your fingers. Most human hairs are around 0.002” (0.05mm) which should give you a good idea of how thick the coatings used on the valves are.   The important takeaway here is that if the coating is only a few thousandths of an inch thick, the valve can only be adjusted a few thousandths of an inch before it will have worn through the coating. Monitoring the starting valve shim size once the engine has been broken in (or new valves installed) and comparing that size to the shims required the next time the clearances are adjusted is a great way to assess valve health. Normally within the first 3-5 hours of breaking in a new engine the valve shim sizes may change slightly. This is due to the mating of the new valves to the seats and any valve seat creep which may occur. After this occurs and the valves have been shimmed to compensate, usually an adjustment up to around 0.004” (0.10mm) is all that can be done before a valve has worn through its hardened surface. Once this happens the valve face will wear much more quickly and start to wear out the seat as well. This will result in more frequent valve shim intervals and necessitate the need for having the valve seats cut. By paying attention to changes in shim sizes you will be able to approximate when the valves have worn through their hardened surfaces and must be replaced.   Thanks for reading and please leave questions or comments below. I enjoy hearing from you!   Remember you can get 300 pages worth of in-depth dirt bike engine information with The Four Stroke Dirt Bike Engine Building Handbook. Be sure to use discount code tt2016 at checkout to receive 15% off your order!   -Paul   DIYMotoFix.com

Paul Olesen

Paul Olesen

 

Everything You Need To Know About The Two-Stroke Cylinder

This week I want to talk about two-strokes. To kick off this post I have some awesome news. The Two Stroke Dirt Bike Engine Building Handbook is off to the printers and will be available for pre-sale very soon! Getting the book off the ground has been no cake walk. It's been two years coming and we are so thankful our riders and fans have been patient with us! At the end of this post I'll give you instructions on how you can stay updated on the launch. With that said, let's get started. Today's post aims to provide an overview of the important aspects of the two-stroke cylinder and answers a couple commonly asked questions relating to cylinder modifications.  

The ports found within a two-stroke cylinder in combination with the exhaust system have the greatest influence on power, torque, and the RPM at which maximum power is created out of the various engine subsystems found within a two-stroke engine. Typically when a new engine is designed the port characteristics are one of the first parameters to optimize. With this being the case they are also one of the first things anyone planning on altering an existing engine should consider improving or tailoring to their specific application. A two-stroke cylinder consists of exhaust, transfer, and occasionally inlet ports (true inlet ports are only found on piston or rotary valve controlled engines). The port heights, widths, areas, directions they flow, and relationships to one another all have a significant influence on how the engine will behave. The cutaway of the cylinder shown details the port arrangement and common nomenclature.

The inlet port/passage delivers air into the engine’s crankcase, most commonly through a reed valve, on a dirt bike engine. On older engines, a rotary valve or the piston may also be used to control the opening and closing of the inlet port. On modern machinery, the inlet simply connects the reed valve to the cylinder or crankcase. In this case, the primary restriction in the inlet port is the reed valve and as such the valve’s geometry and flow capabilities often dictate the inlet port's performance.

The transfer ports are responsible for moving fresh air and fuel up from the crankcase into the cylinder. This occurs as the piston travels downward after the cylinder has fired. Once the piston uncovers the tops of the transfer ports the blowdown phase is complete, at which point much of the exhaust gas has been expelled from the cylinder. As the transfer ports begin to open, the exhaust pipe sucks fresh mixture up through the transfer ports into the cylinder. To a lesser extent, the downward motion of the piston also aids in creating a pressure differential between the crankcase and cylinder. The shapes and flow capabilities of the transfer ports play a big part in how effectively the cylinder can be scavenged of exhaust gases and filled with fresh air and fuel. The transfer ports also help cool the piston. The exhaust ports dictate how much and how well exhaust gases depart the cylinder. Similar to the transfer ports, the duct shape, angle, length and volume have a large influence on how well gases can flow through the port. Typically, dirt bike engines commonly feature bridge port or triple port designs.

General insights into a cylinder’s performance can be made by characterizing attributes such as the timing of the exhaust and transfer ports, the port widths, and the directional flow angles, but a deeper analysis is required to truly optimize a cylinder. Today, tuners and designers rely on computer software which computes a port’s specific time area (STA). As defined in the EngMod 2T software suite, “STA provides an indication of the effective port window area that has to be open for a certain length of time to allow enough gas to flow through the port to achieve the target power at the target RPM for the given engine capacity”. STA values are used to quantify the exhaust, transfer, and inlet port geometry as well as the blowdown phase of the two-stroke cycle. The blowdown phase occurs between exhaust port opening and transfer port opening and is one of the most important parameters in predicting engine performance. By manipulating STA values and subsequently the height, shape, and size of the exhaust, transfer, and intake ports, an engine’s power characteristics can drastically be altered. Port modifications can be made which allow more air to move through the cylinder, ultimately increasing the power of the engine. Conversely, ports can be filled or welded and reshaped which tame the engine and provide less peak power but a broader spread of power. Simple modifications to the ports can also be carried out which improves the air or exhaust gas flow through the port yielding better cylinder scavenging.

Can I modify my own cylinders?
Unless you have a deep passion for two-stroke tuning, are willing to spend money on software and porting equipment, and are comfortable throwing away botched cylinders, I would recommend having a reputable professional carry out any desired port modifications. Experienced tuners have developed a number of porting combinations that will work well for various makes/models and riding applications which will take the guesswork out of the situation and provide you with a good performing cylinder.

Who should consider two-stroke porting modifications?
For the sake of simplicity, I will lump porting modifications into two categories: major and minor. Major port modifications would include tasks such as significantly changing the port timings (by either removing or adding material), altering the shapes of the ports, or changing the directions the ports flow. Anyone drastically altering their engine, such as turning an MX engine into a road racing engine, should consider major porting modifications. Other examples of applications that may require or benefit from major port modifications include drag racing, hare scrambles, ice racing, or desert racing.
  Minor port modifications would include basic tasks such as removing casting flash, slightly altering the ports to achieve the stock port timing, and correcting areas that result in minor flow deficiencies. Just about everyone could benefit from these types of corrective actions; however, if the engine is already performing or producing adequate power, they often aren't considered.  I hope you enjoyed this writeup on key features affecting the performance of two-stroke cylinders. To stay officially updated on The Two Stroke Dirt Bike Engine Building Handbook we created an email sign up for our readers. Click this link to see the new cover, the Table of Contents, and some sneak peek pages right from the book. Thanks for reading and have a great rest of your week! -Paul  

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

 

Now It's Your Turn

How am I doing and what’s on your mind? We are a few posts in I’d like to take a moment to ensure that the most important part of Moto Mind is being taken care of. That part would be you, the reader. Me filling up this blog with content that none of you need or care about would put me on the fast track to having my own online diary! I don’t need a diary for my mental health, I have plenty of fast motorcycles to ride to keep me sane. What I do want is to create a dialogue between you, my readers, and myself so that I can better serve your needs and interests when it comes to your bikes. Over the past four posts I’ve hit on a few topics I feel should benefit all of you. Have you gotten a chance to think about or use them? Any thoughts or tips on your end concerning warming up your engine and piston ring end gap? You guys are the most important part of this dialogue and hearing from you is the ticket to making my time here on Thumper Talk worthwhile. Along with working in some of the content you want to see, I also want to share some of the topics I’m getting pumped to post about. On the technical side, I am going to post an in-depth look at engine balance, continue to post on successful engine building practices, and discuss the importance of keeping a log of the maintenance you perform on your engine. In addition to the technical content I am also planning on taking you through the complete design of a single cylinder two-stroke engine. As I design I am going to explain the process, creating an open door policy on how an engine is designed and why. The two-stroke engine is one of my passions and I would like to see a resurgence of it as a viable powertrain platform for sport vehicles. My aim is to teach you how the two-stroke can be produced using a more clean and efficient design. I hope you’re excited as I am about these upcoming topics. My aim is that this knowledge can serve you as much as it has served me. Give me a holler through the comments below and fill me in on what you want to see more of and what you want to learn about. Moto Mind is merely the sum of its readers and riders. 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

 

Do You Know The Importance of Tightening Techniques?

I hope you’re all enjoying the fall weather. For those of you in northern states, I hope that you’re getting in some end of season riding. This month I want to touch on bolted joints and the importance of adhering to tightening techniques outlined in your model’s service manual.   How A Clamped Joint Works
I’m going to discuss the importance of criss-cross patterns, tightening sequences, incremental steps, and joint lubrication but first I want to explain how a bolted joint works. As a bolt is tightened to secure a pair of parts, the bolt will stretch a very small amount. The stretch in the bolt creates tension or preload in the joint which is the force that keeps the joint together. The amount of preload created is dependent on bolt size, bolt material, the torque applied, and the friction between the threads. There are additional variables, however a discussion on bolt engineering would be very long and not all that exciting! As long as you understand the basics for engine building you can begin to appreciate the importance of correctly tightening fasteners.   As you are well aware, an engine consists of many parts fastened together. What you may not consider as much is that the majority of these parts are fastened by more than one fastener. This means that how much you tighten/preload one fastener will have an effect on the surrounding fasteners. This interaction between the fasteners begins to shed light on why tightening sequences are so important.   The evenness of the preload across the bolts securing a part can affect part life. Warpage can occur in parts which are improperly tightened, ultimately rendering the part useless. A prime example of a part that can warp is a four-stroke cylinder head. If the bolts are unevenly tightened over time, the cylinder head can become permanently distorted. Gasket sealing problems can also occur from improper preloading of bolts across a part. In order for a gasket to seal it must be evenly compressed. If one area of a gasket is highly compressed and tensioned while another area is not, the gasket can easily leak through the low tensioned area. In the case of plain bearing bores, such as the cam cap, uneven preloading may cause the bearing bore to distort. As a result the cam may become difficult to turn. Or if run, the cam bearing bore will wear unevenly and in severe cases the cam could seize.   While ensuring bolt preload is even can be a problem there are three tightening techniques that virtually eliminate the issue. If you’ve been building engines for any length of time you’ve probably already been utilizing these techniques. Hopefully now you may have a better understanding of why the service manual instructs you to tighten parts a specific way.   Criss-Cross Patterns
Criss-cross patterns are called out when tightening or loosening parts with a simple square pattern or circular bolt pattern. These basic patterns have been around for a very long time and are a proven method for evenly distributing clamping load across a part. Most cylinder heads will utilize this type of clamping pattern.

Tightening Sequences
For more complex bolt patterns, such as those found on cam carriers and crankcases, the manufacturer will usually identify a specific sequence for tightening and loosening the fasteners. This sequence is based on testing and the past experiences of the manufacturer.     Incremental Steps
Highly torqued bolts, such as those found on the cylinder head, are almost always tightened and loosened in incremental steps. An incremental tightening sequence consists of torquing all the fasteners to a specific torque value, then increasing the torque and tightening again, and finally arriving at the final torque value. This sequence is typically performed in two to three steps.   Here’s something important to keep in mind regarding incremental steps! When torquing bolts in steps the change in torque between the steps must be large enough to induce bolt movement. For example if a bolt was torqued to 35Nm at the first step and the second step was 38Nm this would not be enough of a change to make the bolt move at the second step. The torque wrench would not overcome the friction of the stationary bolt and would hit 38Nm before the bolt even moves. As a rule of thumb incremental changes should be no less than 5Nm and if possible should be greater.   Lubrication
For highly torqued fasteners often times the service manual will specify that the threads of the fastener must be lubricated. The lubricant can be as simple as fresh engine oil or a specifically formulated thread lubricant product.     Adhering to any lubrication guidelines is of utmost importance. Since we most commonly measure torque to determine whether a bolt has been tightened/preloaded enough any change in the amount of force required to turn the bolt will influence the resulting bolt preload for a given torque value. The force required to turn a bolt is partially dependent on the amount of friction in the joint. If we had two identical fasteners where one was lubricated and the other was not, and we set the torque wrench to the same value for each, then both were tightened, the resulting bolt preload would be different between the two. Due to the reduced friction in the lubricated joint the bolt would stretch more and the preload in the joint would be higher at the specified torque wrench setting than the unlubricated joint. Depending on the criticality of the joint this can be a really big deal! It also shows why in some applications (think two piece conrods) directly measuring bolt stretch is a more accurate means of determining bolt preload.   I hope you enjoyed this quick summary of tightening techniques and their importance! If you have tips of your own you’d like to share or other pearls of wisdom please leave a comment.   For those of you interested in more engine building knowledge check out my book, The Four Stroke Dirt Bike Engine Building Handbook. You’ll find more detailed and comprehensive info on engine building there. Simply follow the links below. Thanks for reading and have a great week!   -Paul     The Four Stroke Dirt Bike Engine Building Handbook   Available on Amazon

Paul Olesen

Paul Olesen

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