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Found 11 results

  1. This is the saga of my poorly maintained 2003 YZ250 that I bought about a year ago. I added a few mods last summer to help me get by then deployed to Africa for 6 months. The poor bike was riddled with SAE hardware, spray foam where there should have been gaskets, and ziptied rear fender, a horribly cut seat, and plenty of other unspeakable things. However, it came with a title and the engine did run pretty strong at the time...even though it had a hint of engine noise. Over time, the noise progressed and I knew what had to be done. While I was away, I coerced my wife into sending a used crankshaft i bought out to Mr. Crankshaft so I'd have a spare for a quick swap... This is it after I replaced the fuel tank that had a split in it and put a lectron carb on. It still wasn't that smooth and the wheel/tire combination were unforgiving, plus, the suspension and rebound were set for a wanna-be-freestyle MX rider. This is the transition to where it was before I really dove in GT216AA Front with Nitro Mousse 18" Rear with Shinko 505 Cheater rear and Nitro Mousse Low Enduro bend Flexx bars (eventually putting steering dampener on) SSS Forks and suspension done by W.E.R. DEP Armored Enduro Pipe Steahly 9oz Flywheel Weight Devol Skidplate IMS/Zipty tank Non-cracked white rear fender Tall seat...I forget who made it, but it does what it do and fits well. Head cut by 218 (head was cut after this photo was taken) rock kickstand During this ride, I had next to no bottom end due to a stuck powervalve. This was my first ride since I came home. I never really tore into the engine, so I got in there, cleaned it up and replaced a broken powervalve pulley and a few areas where parts were missing from the previous owner(s). Two weeks after this picture, I took it out to the mountains for the fourth of july and it started to get real nasty sounding and not in a good way This is why: While I was in there, I figured I'd send the top end out to Eric Gorr...and since that has a 2.5 week lead time, I might as well get the frame in order. Now my bike looks like this. The frame was spray bombed over who knows what, which was over the the original finish. That is being re-mediated. To be continued...
  2. Today I want to share some pointers on preparing new or re-plated cylinders that will help ensure your engines run stronger and last longer. Plus, I've got an update on the two-stroke book I've been working on that I'd like to share. Let's get started! A Universal Concern First, both new and re-plated cylinders must be cleaned prior to assembling. Normally the cylinders will arrive looking clean, but looks can be deceiving. I have no doubt that the factories and re-plating services clean the cylinders as part of their processes, but I highly recommend cleaning the bores a final time prior to use. Shown below is a new Yamaha cylinder that I extracted quite a bit of honing grit out of. If left in place, the honing grit will ensure that the piston rings will wear out faster than they need to, so be sure to take the time to properly clean new cylinders prior to assembly. What’s the best way to clean the cylinder bore? Start by using warm soapy water and a brush to clean the cylinder. Take your time and be thorough. After the majority of the honing grit has been removed switch to automatic transmission fluid and a lint free rag for one final cleaning. As a test to check cleanliness, rub a cotton swab against the cylinder bore. If the swab picks up any debris and changes color, your cleaning duties are not over. The swab should be able to be rubbed against the bore and remain perfectly clean. Two-Stroke Port Dressing For two-stroke owners, the second item I want to bring to your attention is port dressing. Port dressing is a term used to describe the process of deburring/breaking the edge at the intersection of the cylinder plating and the ports in the cylinder. During the plating process, plating usually builds up excessively at the edge of the port and must be removed after honing. Proper removal is critical to ensure acceptable piston ring life. Manufacturers and plating services will break the edge in different ways and to different magnitudes, which ends up being a whole other topic. The important thing is to ensure that any new or re-plated cylinder you use shows visible signs that the port edges have been dressed. A dressed port edge will be easy to spot because it will feature a different surface finish than the cross-hatch created from honing. This is easily visible in the image shown above. Many port dressing operations are done manually so some irregularity in the geometry will usually be present. If there is no visible edge break on the port edges, I would be highly suspicious and contact the service that plated the cylinder or sold the cylinder and confirm with them if a step was missed. Typically a chamfer or radius in the .020 - .040” (0.5 - 1mm) range is used. Two-Stroke Power Valves Lastly, it is possible that some of the power valve components, such as blades or drums, will not fit correctly on cylinders that have been replated. This is because the plating can occasionally build up in the slots or bores where the power valve parts reside. Prior to final assembly, be sure to check the function of the power valve blade and/or drums to ensure they move freely in their respective locations within the cylinder. If plating has built up in a power valve slot or bore, it will need to be carefully removed. To do this, appropriately sized burs for die grinders or Dremel tools can be used. If one is not careful, irreversible damage to the slot or bore can result. When performing this work proceed cautiously or leave it to a seasoned professional. Burs for the job can be difficult to track down in stores, but are readily available online from places like McMaster-Carr. When purchasing burs, be sure to pick up a few variants, such as rounded and square edged, designed for removing hard materials. The Two-Stroke Book From February to March we photographed the entire book. From April onward we have been formatting and proofreading. Needless to say, we are in the final stretch! If you want to stay updated on the moment the Two-Stroke Dirt Bike Engine Building Handbook is ready for pre-order, sign up at the link below. We can't wait to get this book out the door and into your garage. Sign Up for Updates on the Two-Stroke Book Thanks for reading and have a great rest of your week! -Paul
  3. Looking at getting a new bike and keep on bouncing back and fourth between the 2017 beta and Sherco for a 300 two stroke. I have owned ktm, yamaha and husqvarna and want to try something new that no one else i ride with has. The oil injection really has me interested in the beta along with the adjustable powervalve and the kickstart is nice to have for piece of mind. But i like the looks of the sherco better, larger fuel tank is handy and have heard really good things about them. Just curious on what personal experience you guys have on them, pros and cons of each to try and persuade me to pick one. I think it will end up being a coin toss to decide in the end.?
  4. KTM introduced its lastest EXC models at the iconic Erzberg in Austria. For more information visit http://www.ktm.com/enduro
  5. I hope you all have been out riding and enjoying spring. I got back into the hare scramble racing scene over the weekend after a three year hiatus and had a blast. Today, I just want to share a quick tip and start a discussion on preparatory things that help shorten the time it takes to do complex maintenance tasks, such as rebuilding an engine. Quick Tip Prior to turning a wrench carefully look over the service manual scanning through all the applicable procedures and subsystems. If I’m working on an unfamiliar model, I find it is helpful to jot down a rough outline of the disassembly sequence. This saves me time in the long run as I don’t have to rely as heavily on the service manual or continually flip through various sections. Another option is to use post-it notes to bookmark each relevant section in the manual. Mark the post-it notes with numbers or headings so you know where to turn to next. Earmarking or bookmarking the torque tables is also a huge time saver no matter the task. Be sure to scan through the manual as well to identify any specialty tools that are required that you may not have. Discussion Points What other preparatory things can be done to help speed up the major maintenance process? Is there a method to your madness or do you dive right in? Thanks for reading! Paul https://www.diymotofix.com/
  6. My 1999 CR 125 has been loosing coolant. Theres some leakage around the water pump. Is this a problem with the head gasket? Would this cause any kind of power loss?
  7. Hey guys, I'm new to thumper, but I was hoping I could find someone who could help me. HERES THE DEAL! I've been riding 4 strokes for about 7 years now, but the 2T world has recently gotten my attention! I currently ride a 2006 YZ250F. (Fully rebuilt by myself;). I ride the piss out of it and I feel like it's missing something. I've tried shaking things up like riding different terrain(sand dunes,Rocks,etc.) I thought maybe I would try a 450, I got to ride my buddies CRF450X. lol that bike humbled me. It was way to high and It felt a LOT heavier. I crossed out the 450 bc I think it would be a waste and I wouldn't be able to push the bike to its limits. With that being said I'm trying to decide between (2017 Ktm 150 sx, 2017 Ktm 250sx, and 2017 YZ250 and/or the X model). Here's me.. I'm roughly 5'8" 175-185lbs. I lift 5-6 days a week. I enjoy riding anything and everything as long as I get to ride.
  8. 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!
  9. I was riding my bike at full throttle doing slides in the sand and then suddenly my bike started bogging. It seemed incredibly lean like it was running out of gas. Full throttle barley even got it to accelerate at all. I filled it up with gas and no luck. Any ideas what happened?
  10. i have a very beautiful 2004 kx125, i picked it up a few months ago and when i got to the guys place to check it out, he started it by foot like normal and i rode it around the yard and about 500 feet i went and brrrrrrrr it fouled the plug??? but it was 1800$ so i was like heck with it im still getting it to the looks of the condition and claimed recent rebuild. i took it home and we replaced the spark plug and we had to bumpstart it this time. again 500 feet and brrrr fouled. this bike has a BRAND NEW mikuni carbourator OEM with jetting and airscrew position on point, Timing is perfect, i even tried advancing and retarding the timing, still nothing. i put it back in its normal position though. Reeds are good. no gasket leeks. good compresion. spark plug is BR9EIX NGK. it gets a spark, its getting gas, its getting air. when i try and start it, it back fires sometimes a loud pop. carb should be out of question, timing should be out of question. what else is there to check? i have talked to a few people saying it might be either, crank seals, or the stator. but i have NO IDEA of what to do. please help me i know u guys might know what to do, im 15 and trying to get into mechanics and i try to be the best mechanic i could possibly be with my hard earned tools. 4/1/17 ill be checking on any comments or suggestions every 8 hours or so. and i also dont want to buy new parts for the bike that it doesnt need. Thanks for reading! give me your best shot, I accept any help!
  11. 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 If enjoyed this post be sure to follow my blog and sign up for my newsletter! DIY Moto Fix Newsletter