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Paul Olesen

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About Paul Olesen

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    TT Powertrain Expert

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  • Gender
    Male
  • Location
    Wisconsin
  • Interests
    Racing motorcycles, engine design, homebuilt motorcycles, engine building, traveling, flying, backcountry snowmobiling, water sports, downhill mountain biking, reading, and films

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  1. Paul Olesen

    Are Project Bikes Even Worth It?

    You bring up a good point, the $2400 has not been spent and is what has been budgeted. If I can acquire parts cheaper than what I've budgeted I'm in better shape, if I have to spend more, I'm worse off. Based on my initial inspection my cost estimates include what I think needs to be serviced to make the bike operable. The additional items you've laid out would fall into maintenance costs, in my opinion, which every bike will have on an annual basis. Thank you for the lead on a cheaper cylinder option! For those looking at buying used bikes, we also put together a comprehensive buying guide: https://www.diymotofix.com/freebies.html
  2. Paul Olesen

    Are Project Bikes Even Worth It?

    You can look at it that way, however, in this case, upon inspection of the suspension, there were no signs that immediate servicing is required. Since I've made that call, I view it as a maintenance cost that should be allocated to bike ownership whether pre-existing or newly acquired which would occur in the off-season. The cost estimates I've shared address issues that keep the bike from being operable. If you were inclined to do the suspension work right away it would add 100-200 dollars depending on who is doing the work and what, if any, issues are found.
  3. Paul Olesen

    Are Project Bikes Even Worth It?

    Thanks, I'm glad you enjoyed the article! Your engine doesn't have to seem complicated, I wrote the two and four stroke engine building handbooks to take the complication away. Please check them out here: https://www.diymotofix.com/books.html
  4. Paul Olesen

    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
  5. Can i bypas the choke on yam 66o raptor cadbs? Is there a vacume leak if the cable screw on the carb is missing.cRbs are on a xt 600 bored to 630cc

     

  6. 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/
  7. Paul Olesen

    How to Separate Your Crankcases The Right Way

    You're welcome. Tusk and Pit Posse offer splitters in the $50-60 range which I would recommend. If you want a really nice one you might consider the Motion Pro, however, you'll be spending about 3X more.
  8. Paul Olesen

    How to Separate Your Crankcases The Right Way

    “Splitting the cases” is often referred to as a daunting or undesirable task, but if you are well prepared and properly equipped then it can be a straightforward job. To alleviate any concerns you may have with the task, I want to discuss best practices and share some tips that you may find useful when dealing with crank bearings that utilize an interference fit with the crankshaft. We’ll get started by discussing preparatory items and work through to completing the job. Preparation I always recommend prepping for crankcase separation by thoroughly reviewing the service manual. This is important in case any special instructions are present, such as guidance on how the crankcases should be positioned. Typically, it is advantageous to lift one half off the other in a certain orientation due to the way the gearbox or other components are installed. Secondly, a review of the manual may highlight any specific hardware that must be removed prior to attempting to split the cases. From a tools standpoint, a crankcase splitter tool is a worthy investment because it will help ensure the job goes smoothly. Case splitters are relatively inexpensive and widely available. Alternatively, for the budget conscious or lesser prepared, a case splitter is something that could be fabricated. Whether buying or making, ensure you pick up a model with a protective end cap for the crankshaft or fabricate one. We’ll discuss the end cap later. The other tools required are all fairly standard and include your typical sockets, wrenches, and soft mallets. Wooden blocks or other soft semi-malleable spacers should be selected which level and raise the crankcases off the tabletop. This allows the cases to be positioned so that the split line between the cases lies horizontally and subsequent splitting can be done vertically. This will help ensure evenness of separation as well as reduce the likelihood of components falling out of the cases unexpectedly. As much as shortcuts are desirable, just about everything external to the cases must be removed in order to successfully split the cases. Clutch, stator, crank gear, etc. must be removed prior to case splitting. Your service manual will provide further clarity as to what needs to come off. Technique & Tips Once you’re ready to separate the cases, the first thing we’ll need to do is remove all the crankcase bolts. The crankcase bolts should be removed via any prescribed patterns outlined in the service manual. Since the crankcase bolts are typically several different lengths, ensuring the location of each bolt is well documented is extremely important. As I discussed in my post on keeping track of bolts, the cardboard gasket method or any other you find suitable should be utilized so that the reassembly process is straightforward later on. After the crankcase bolts have been removed, the crankcases should be inspected one final time to ensure no hardware that should have been removed prior is hitchhiking. Trust me, trying to separate cases only to find there is one last forgotten bolt is quite frustrating! Once you’re confident all the necessary hardware has been removed, position the cases on the blocks with the correct half facing up. Next, install the protective cap over the crankshaft. I advise using the cap whether you own a two or four-stroke simply because in both cases it helps preserve the end of the crankshaft. This is of particular importance on four-stroke engines that utilize an oil feed that passes through the crank. Once the crank end is protected, proceed to install the crankcase splitter. Select threaded holes that are as close to equispaced from one another as possible to promote uniform loading of the case splitter. When threading the case splitter studs into the crankcase, make sure you engage at least 1.5 times the diameter of the stud diameter. For example, if the stud is 6mm in diameter make sure at least 9mm of thread engagement length is achieved. This will help ensure the threads are not stripped when you attempt to separate the crankcases. With the crankcase splitter installed begin tensioning the main bolt against the end of the protective cap. Proceed to tighten the bolt until the crankcases begin to separate about a 1/16” (1.5mm). Once separation has occurred, make sure that separation is even all the way around the cases. Due to the way the case splitter loads the cases, the area near the output sprocket tends to lag. Case separation needs to be even so that the dowel pins used to pair the cases together don’t bind. If the output sprocket end of the cases hasn’t separated, use a soft rubber or plastic mallet to gently tap in that area. Tap carefully and only on case areas that appear sturdy. Once you’ve created an even gap, proceed to tension the splitter bolt, tap when necessary, and fully remove the crankcase. Upon separation, make sure that no gearbox components, such as washers, have stuck to the case. What I’ve described is the ideal sequence of events for a successful case separation, however, occasionally the cases won’t be as cooperative. In the past, I’ve had to deal with crankcases where moisture has found its way into the dowel pin bores and corroded the dowel pins. This effectively seizes the dowel pins in their bores and makes the separation job more challenging. If the crankcases are being resilient to separation, stuck dowel pins may be a potential problem. Most dowel pins are located opposite one another and their exact position can often be referenced in the service manual or in the crankcase section of part microfiches. Once the location of the dowel pins has been confirmed, a torch can be used to lightly heat the dowel pin areas. Heat will expand the metal surrounding the dowel pin and aid in freeing up the stuck pin bore. Usually, a few careful rounds of heat, tension on the splitter, and well-placed tapping is enough to free up the pesky cases and get them separated. Alternatively, if the heat does not help, applying a penetrant to the pin bore areas is another option that may help free things up. If you find yourself dealing with stuck cases, the key is to be patient and think through all your options. In these types of situations, most mistakes are avoidable and are usually the result of rushed decisions. Once the cases have been separated, the remaining tasks of removing the gearbox and pushing the crank out of the remaining case half can commence. I hope you’ve enjoyed this write up on crankcase separation and that it makes you more prepared for the job. If you’ve got additional crankcase separation tips that you want to share, please leave a comment below. For additional engine building information, whether two or four-stroke, check out my engine building handbooks. Each handbook is offered in print or digital form, contains over 250 color pictures, detailed instruction from start to finish on full rebuilds, and contains a wealth of information pertaining to diagnostic testing and precision measuring. Thanks and have a great week! -Paul
  9. Paul Olesen

    The Two Stroke Dirt Bike Engine Building Handbook is Here!

    Thanks for your support, I hope you enjoy the book! Thanks for your support!
  10. In today's post, I'm very excited to share details about my new book,The Two Stroke Dirt Bike Engine Building Handbook. As with all of my blogs and technical resources, my goal has been to bring riders clear and concise technical information. My two-stroke book exemplifies this and puts nearly 300 pages of engine building knowledge at your fingertips. I wroteThe Two Stroke Dirt Bike Engine Building Handbook to be an all-encompassing guide on engine building. From the moment there is doubt about the engine's overall condition to the time the rebuilt engine is broken in, I give you a step-by-step guide to help you work towards a successful build. My aim was to create a definitive resource that hit on all the relevant topics you'll encounter as you proceed through an engine build and take any guesswork out of the equation. Throughout the book, engineering knowledge and practical experience are fused together to detail the how and why behind the way procedures are performed, parts are designed, and engine performance is affected. This is the most important and valuable aspect of the book, and it's something you won't find in a service manual. The book doesn't just tell you to bolt part A to part B, it teaches and explains the correct way assembly procedures should be performed and why it is necessary to do so. It also explains the intricate relationship between parts, where to look for wear patterns, and shows examples of worn and damaged components. If you're interested in making modifications to your engine or if you're curious about how certain modifications affect performance, I wrote an entire chapter dedicated to the subject. Within this chapter a discussion on how performance parts such as expansion chambers, port timing modifications, and cylinder heads alter overall engine performance is included and helpful suggestions are provided to aid you in choosing the correct components for your build, depending on your specific riding needs. If you have a thirst to learn more about how your engine works and a desire to correctly disassemble or assemble an engine to professional standards, you will benefit greatly from this book. Whether a complete beginner or a seasoned builder, with nearly 300 pages and 250 images worth of information, there is fresh and useful knowledge for everyone. There is also valuable material packed into this handbook that doesn't just pertain to the act of building the engine. I include instruction on diagnosing engine problems, sourcing and determining which parts to replace, using precision measuring tools, setting up your workshop, and additional tests and inspections that should be performed when preparing racing engines. If you just want to build your engine back up to stock spec, you are covered. If you want to go the extra mile and prepare a racing engine, you are also covered. In a way, this book allows you to choose your own ending by giving you all the tools and knowledge you need to complete your build at whatever level you decide. As a way to thank you for your support, we're offering TT members 15% off during a special TT pre-sale which runs from now until December 5th (when the book officially launches). Simply follow this link to learn more and order: ThumperTalk Pre-Sale Thanks again for all your support as we've grown DIY Moto Fix from an idea to a thriving community of riders who are passionate about making their machines perform better through their own hard work. Thanks for reading and have a great week. -Paul
  11. Happy Birthday ya old dog! ;)
    a97635_sam2.jpg

  12. Paul Olesen

    The Four Stroke Dirt Bike Engine Building Handbook

    Hi Scott, thanks for picking up a copy of my book! It's great to hear the booking is helping you out.
  13. Paul Olesen

    The Four Stroke Dirt Bike Engine Building Handbook

    Hi Jakob, Our book is not distributed to any physical stores, however, it is available through our website and we ship internationally. Paul
  14. Paul Olesen

    How The Two-Stroke Exhaust System Works

    In my last post, I shared details about how the two-stroke cylinder works, in today's post I want to provide an overview of how a performance two-stroke engine's exhaust system works. Adding a performance exhaust system can be a great way to increase power and/or alter the power delivery of an engine. I would also argue that optimizing a two-stroke engine’s exhaust system is equally as important as ensuring the cylinder’s ports are correctly designed for the given application. Not all exhaust systems are designed to do the same things, and much like cylinder port design, exhaust designs are intended to alter power in specific ways. Having a basic understanding of how an exhaust system works can go a long way when it comes to selecting the right exhaust pipe for your engine. Two-stroke exhaust design is complicated and there are many different variables that must be considered when designing a pipe. I don’t intend to go into all of them, but I will share a few of the most critical. Each time the exhaust port opens to release spent combustion gases, pressure pulses are created. Modern pipe designs harness this pulse energy and use it to help scavenge and fill the cylinder. The process starts when a positive pressure pulse is created once the exhaust port opens and combustion gases leave the cylinder. The positive pulse travels down the pipe until it reaches the diffuser, at which point part of the pulse is inverted and reflected back towards the cylinder as a negative wave. This negative wave is very beneficial in pulling spent exhaust gases out of the cylinder and fresh mixture up through the transfer ports. The remaining positive pulse continues on its journey towards the end of the pipe where it encounters the reflector. The reflector acts as the name implies and forces the positive pulse back towards the exhaust port. Once reflected back, the pulse remains positive and, if the pipe is designed correctly, will reach the exhaust port just as the piston is about to close off the port on the compression stroke at the desired RPM for maximum power. Any fresh mixture which has escaped out the cylinder will be forced back in by the positive pressure pulse. The tuned length of the pipe is dictated by the exhaust port timing, RPM of max power, and the speed of sound. Pulse length and amplitude are governed by the angles of the diffuser and reflector. Generally, steeper cone angles create pulses with more amplitude but shorter duration. Shallower angles generate pulses with less amplitude but longer duration. Given these variables, it is easy to see how a pipe could be tailored for specific applications. An engine converted for road racing may utilize a pipe designed for peak power which incorporates steep diffuser and reflector cone angles so that pulse amplitude is not sacrificed. This peak power would likely come at the expense of a narrowed range of power. An engine tailored for woods riding may feature a pipe with shallower cone angles, resulting in less pulse amplitude, but a broader spread of power. The last parameter I want to touch on is how the tailpipe, which is sometimes referred to as the stinger, influences the pipe. The tailpipe creates a flow restriction in the pipe which allows the pipe to have a certain amount of back pressure. Enlarge the tailpipe and the back pressure decreases, make it smaller and the back pressure increases. As back pressure increases or decreases, so does temperature and ultimately the speed of sound. As the speed of sound changes, so does the resonance RPM of the pipe. If the tailpipe is sized too small, cylinder scavenging will be inhibited. When this happens, the cylinder, fresh mixture, and piston will all be overheated. While engineers and tuners can estimate starting pipe dimensions and tuned lengths, a great deal of trial and error testing is usually still necessary to fine tune the exhaust pipe and optimize the design. Unless you intend on building your own exhausts, this work will have already been done for you. When selecting an exhaust system, you need to focus on how the exhaust alters the power curve. Exhaust systems are tailored to deliver more bottom end performance, top-end performance, or performance throughout the power curve. Selecting which system is right for you will depend on how you want your engine to perform. If you’ve chosen to modify your cylinder ports, installing an exhaust system that compliments the porting can be very beneficial. You might be wondering about slip-on mufflers. If you’ve followed along with my explanation of how exhaust pipes work, you’ll notice I made no mention of the muffler. While the muffler can have a small effect on performance, it is not the primary factor. Upgrading a muffler is a good way to reduce weight, but there won’t be a slip-on out there which significantly increases power, in the same way, a properly designed expansion chamber can. I hope you enjoyed this write-up on key features affecting the performance of two-stroke cylinders. As for Two Stroke Handbook news, we received our first printed proof of the book this week! Needless to say, we are inching closer and closer to an official release date. To stay updated on The Two Stroke Dirt Bike Engine Building Handbook we created an email sign up for our readers. Click this link to sign up, 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
  15. Paul Olesen

    Everything You Need To Know About The Two-Stroke Cylinder

    You're welcome, I'm glad you enjoyed the article.
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