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Found 618 results

  1. Hello all, I have begun the tear down of my recently purchased 2007 CR125. It has been ridden once since I purchased it. The piston is about to go (approx 50 psi on compression test). I have already submitted a few questions on TT, but thought it would be easier to pull them all into one thread. Here are the most recent threads about the build and from here on out, I will just post questions and relay my progress here. The other day, my son removed the engine as we are going to replace the top end (still stock OEM, engine has never been opened). Naturally, I have to clean the entire bike now since the engine is out, but that is a bit later. While I am replacing the top end, I am going to go ahead and replace seals and all gaskets (minus splitting the engine). As I was starting to tear down the engine to look at the condition, I notice that the fly wheel has some rust on it, which is not good (see pic below). Question is, should I just try to remove the flywheel, clean it up really good and reinstall or replace it all together? It seems mostly surface rust. It looks like maybe some moisture got in through the cracks in the rubber wire cover around the case boot area (see pic). I need to address that as well, but it appears the only way to fix it is to get an entirely new wiring harness which is $400!!! Any thoughts and comments would be greatly appreciated. Unfortunately, I will be away from the bike for 10 days (Traveling to Ireland), but plan to put together a shopping list from RMATV and/or Partzilla during the long flight over so the parts will be waiting for me when I return. More progress to come!!
  2. Have a 2015 YZ125. After a rather bad crash I had to replace the subframe and air box. I put it all back together. Kicked for 5 minutes Wouldn't even come close to starting. Had been sitting for 6 weeks or so, so I checked and Got spark, got compression, got new plug(old one showed proper color, not lean), got gas supply to carb. Anyway I lay the bike on its left side for a highly technical excess fuel purge and first kick with fuel off and zero throttle, it starts but have runaway engine condition. Had to use kill switch to stop it before it blew up. I have been reading that it could be crank seals or another type of air leak. Not really buying that because why would it start right up after simply laying it on its side. New air box should be sound and sealed. Anyway I would think the air leak if it's that is after the carburetor. On the YZ there is only the reed valve after the carb. I'm thinking crud in the carb but on a dirt bike you would think that would be a more common condition. Anyway, looking for ideas here.
  3. Time Left: 11 days and 2 hours

    • WANTED
    • USED

    im looking to buy a cylinder that will fit a 98 kx250 u purchased a bike that doesnt have one at all so i need one complete with the power valve setup as well. if you know where one is or have one or any other kx250 parts let me know

    $0.01

  4. Whats up everyone I'm pretty new to the forum so I'm not sure if I'm posting in the correct spot.Either way I need some help! what year kickstart levers will fit my 2007 yz450f. I got away with a Kim lever off a 525 exc but now I'm looking online and can't find much but one option for 130$ I'm seeing a lot of options for 2011 levers around 75$ and they look nicer with a blue instead of silver. Does anyone know what size the spline is? what other years I could possibly use? thanks in advance. On another note my oil filter housing bolt is stripped like most I see are dealing with. I have googled away and cannot seem to find where to order that bolt.
  5. I just bought a 1997 yz125, lots of racing parts, bike runs AMAZING, starts first kick without choke. Only issue I have is I went out to ride today and when I shifted to second, I hear a clanking sound and can feel the bike trying to grab but it won't. I just replaced the clutch oil filled correctly with 10w-30 oil of the right grade, and the sprockets and chain are good. It's not the clutch because it rides perfect in all the other gears, 2nd is just garbage though. I know I have to split the case for this, but has anyone had any experience with an issue like this, or have any tips to share? I've found both gears on ebay for 2nd, and can get them both for under $100 combined, just don't want to pay $300 for my shop to split the engine. What specialty tools do I NEED, and what can I make do without? Thanks in advance!
  6. Hey guys, was hoping someone could help me identify what year my engine is? I was told the bike was a 99, turned out to be a 96. But when replacing my top end, a 96 piston doesn't fit. So was hoping someone could help. The vin on the casing is "J115-103439" Thanks!
  7. Hi, i am just looking for some advice regarding what year crank cases will fit my 2012 Yz250f, at the moment there is a small crack in the main bearing housing on the right hank crank case and i am looking at a picture online of a 2006 right crank case and they look identical. i know a 2005 case wont fit because of a different sump but will the 2006 or above fit? Thanks in advance, Ben
  8. I'm currently in the middle of giving my two stroke motor a full overhaul because the big end rod bearing is worn. I'm just curious how many of you replace every single bearing in the engine while it's split or if you only replace them if they show signs of wear/damage?
  9. Just bought a new 09 Kawk 250. Motor will get going with the choke, on a cold start. After warm up (15min+ driving) motor will sometimes start without the choke BUT a lot of the time won't start without the choke. no rich smell from the exhaust, no gas smell .... should it do this? I'm a new motorcyclist don't know much about motorcycle engines, just cars and small utility engines
  10. dr

    Hey everyone. I've just started to ride my dr650 again after about a 6 month break. As I was taking it down a back road I started to hear a rattle coming from the left side of the bike. At first I could only hear it in 1st gear, after I got back to the main road I could hear it in the lower gears. Where there wasn't a whole lot of noise hiding it. It doesn't do it on smooth roads, and it doesn't do it while idling. At first I thought it might be my home made foot pegs. Alas it still did it even as I was holding them still. Also on the left side the engine is getting very hot fairly quickly. I'm currently waiting for the engine to cool off to knock things aroubd and see if i can find something loose. In the meantime I've been looking up the symptoms and some posts mention the heat shield, but since it isn't rev specific I don't think that's it. Any ideas anyone?
  11. Bike's still giving me the middle finger after a top end rebuild and camshaft replacement. I've ruled out the decompression system as the culprit but am now back to square one with one big clue. It's something in the crankcase.... joy. Got a video of it doing it's thing as well. Sounds alright when it's putting around, but when you get on the throttle things start clacking around and the moment you pull in the clutch and allow the motor to spin freely it dies. Engine failure happens at 1:25 in the video and dies again at the end but no clacking that time. If anyone has an idea of where to start, or a specific part to start with please let me know. I'm in way over my head here.
  12. So basically, i went and bought a honda oil change kit and it came with 10w-30 semi synthetic. So i used it and i feel like the engine is running far too hot and the moving components are so damn loud. So i went ahead and bought some shell helix ultra 5w-40 and i just wanted to know what everyone thinks about it and if he honda ht4 10w-30 oil i got is any good
  13. Hi everyone. Hoping to get some feedback on others' experiences with no toil air filter oil. Here's the scoop. I've used Bel-Ray air filter oil since I was taught how to prep an air filter years ago. Since that day, I've had four bikes over the course of the last 8 years and have never had a bike blow up or have any dirt get past the filter, no matter the conditions. A few months back, I spent some time riding out in Ohio where a friend of mine mentioned that he had great luck with using the biodegradable no toil air filter oil and grease and that it made cleaning filters boatloads easier. I figured I would give it a shot and after the first use I was hooked because of how easy cleaning filters became (no toil powder and warm water). After using it on my '11 CRF450 filters for several months, I was very satisfied and even did some recommending of my own on the stuff. I decided to part ways with the 450 and bought a brand new '14 YZ250 when I came home to Massachusetts. Well, my YZ didn't last more than 4.7 hours before she blew and low and behold, sand got past the filter and had some fun in the cylinder. So my question is, has anyone else had problems with the biodegradable no toil filter oil that I'm mentioning? In my own opinion, I'm thinking that the hard packed Ohio dirt made for great air filter results upon my initial experiences with the product, but the fine sand of the tracks here in MA had something else in store for putting the oil to the test. Since my bike blew and I've sought out every opinion I can from other riders, I'm getting "Oh yeah that no toil stuff is junk" and I'm wondering if others can attest to that. I know some may say "well maybe you didn't grease enough or oil enough" or "maybe the oil settled to the bottom of the filter cause it sat" but I can assure you the filter (which was done the day of my ride) was oiled and greased just as well as any filter I've done over the last 8 years. Just looking to hear others' results! Thanks in advance! (This is the result. 4.7 hours.... this hurts)
  14. Hi, i was wondering if anyone could tell me if a cylinder kit for a 1990 YZ 250 would fit in a 1999 YZ 250. If anyone could help me out ASAP I would greatly appreciate it. Thanks, Maksym
  15. I just bought a 2004 ktm 125sx and it is a very clean bike. I have ridden it only a few times and i noticed a weird studder or kind of bog when in mid to high rpms and the bike cuts out for a second and then cuts back in a split second. I cant figure out what it is doing this. I keep air filter clean, new spark plug, good gas. I use an NGK BR9es, the manual says to use NGk Br9evx. i have read it could be powervalve, jetting, maybe silencer packing, im not sure. please ask any questions, i really want to figure this out. thanks
  16. I recently rebuilt my 06 yz450. Top end valves springs valves seals. That was about a month ago. And I just put in a new spark plug and the bike idled high while riding. So I would let off the throttle and it would go or if in neutral rev high. Now I took everything apart the whole top end and everything looks good. Put it all back together and now the bike barely has any compression and will not start. Carb is clean just took it fully apart. Also the rev limiter is slow not rapid like normal... Just need some help ??
  17. Today I'm going to cover how to check and set cam timing, which is something you can do if you have adjustable cam gears in your engine. This is a procedure often performed by race engine builders to ensure the valvetrain performs just as they intend, and ultimately so that they extract the desired performance out of the engine. Adjustable cam gears typically aren't a stock option but are abundantly available in the aftermarket. The following text is exerted from my book, The Four Stroke Dirt Bike Engine Building Handbook, so if you find this info valuable please take a look at the entire book. Degreeing the camshafts is the process of checking, and if necessary altering, the cam timing so that the timing is set perfectly to specified timing values. On stock and performance engines, cam timing can be off slightly due to manufacturing variations in parts such as the camshafts, cam gears, cam chain, cylinder, cylinder head, crankshaft, crankcase, and gaskets. With so many parts having an influence on cam timing, it is necessary to adjust and correct the timing so it coincides precisely with the desired timing values. The biggest factor determining how the camshafts must be timed is whether the cam lobes are symmetrical or asymmetrical. Camshaft lobes that are symmetrical have opening and closing ramps that share the same profile. Asymmetrical cam lobes have opening and closing ramps with different profiles. Symmetric and asymmetric camshafts are timed differently. First we will focus on the timing of symmetrical camshafts. Symmetric camshafts are timed most accurately by determining the position of the camshaft’s lobe center in relation to crankshaft position. A camshaft’s lobe center is where peak lift occurs, which is the most important timing event of the camshaft. Since the tip of the camshaft is rounded, it would be difficult to determine the lobe center by taking a direct measurement of peak valve lift. The opening and closing points of the camshaft are also of little use because the cam opens and closes gradually. This makes it difficult to determine the precise position in which the camshaft opens or closes the valves. The lobe center position is a calculated value based on the position of the camshaft at two specific points of valve lift, typically with valve clearances set to zero. Normally the position of the camshaft is recorded at 0.050” (1.27mm) of lift as the valve opens and 0.050” (1.27mm) of lift when the valve closes. By recording the position of the camshaft at a specific valve lifts, the cam lobe is on a predictable portion of the opening and closing ramps. The center of the cam lobe is exactly in the middle of these two measurements. To calculate the lobe center of a symmetrical cam lobe you will need to do the following: 1. Add the measured opening and closing timings together 2. Add 180 degrees to the sum 3. Divide the answer by 2 4. Subtract the smaller value of the two opening and closing numbers from the answer to reach the lobe center value. Once the actual lobe center value has been determined on the engine, it can be compared to the specified lobe center timing presented by the manufacturer, aftermarket cam supplier, or the engine tuner. If the measured lobe center position coincides with the targeted position, all the work is done. If not, the cam gear will need to be adjusted so the timing is corrected. If you are checking the timing on stock cams and lobe center information isn't presented, you will need to determine the lobe centers the manufacturer recommends. To do this, the opening and closing timing information supplied in the service manual can be used. Aftermarket camshafts should come with a timing card full of useful information to set the cams correctly if they are adjustable, otherwise the lobe centerline can be calculated if the opening and closing timings are known. If you don’t like math, there are plenty of lobe center calculators available on the internet you can use. For the Kawasaki KX250F engine with the stock camshafts, the timing information is as follows: Intake Opens 40° BTDC (Before Top Dead Center) Intake Closes 72° ATDC (After Top Dead Center) Intake Lobe Center = ((40 + 72 + 180) ÷ 2) - 40 = 106° My calculated lobe center timing is 106°. When I check the cam timing, this will be the value the real engine hopefully yields. The lobe center for the exhaust cam can be found the same way. For the KX250F exhaust cam: Exhaust Opens 69° BBDC (Before Bottom Dead Center) Exhaust Closes 49° ATDC (After Top Dead Center) Exhaust Lobe Center = ((69 + 49 + 180) ÷ 2) - 49 = 100° Something not obvious I want to touch on is that if the intake opens after top dead center, a negative value for the opening should be used. If the exhaust closes before top dead center, a negative value should be used here as well. To start the process of checking the timing the valve clearances should be set to zero. Thicker shims can be used and zero clearance can be confirmed with a lash gauge. A degree wheel and pointer will need to be installed on the engine. There are many ways of attaching these items and each engine will provide its own challenges. Here I’ve left the flywheel on and installed a couple washers behind the degree wheel to space the degree wheel from the flywheel. Then the flywheel nut is used to secure the degree wheel. The pointer can be made from welding rod, a coat hanger, or anything else you can find. I’ll be finding TDC with the cylinder head installed, so I used one of the exterior head bolts to secure the pointer. If you will be finding TDC with the head off, choose another location. Before the cams can be timed, TDC must be found. This can be done with the cylinder head on or off depending on the process you use. The piston dwells a few degrees at TDC so more accuracy than zeroing the degree wheel to the piston’s highest position is necessary. Similar to finding the cam lobe center, TDC can be found by measuring equal distances on the piston’s up and down stroke and then confirming that the degree wheel timing is equal on both sides at the measured distances. Dial indicators or piston stoppers are commonly used to do this. HOT TIP: Piston stoppers can easily be made by removing the center section of a spark plug and then tapping a suitably sized threaded hole in the remaining part of the plug so a bolt and lock nut can be installed. The stopper can then be easily threaded into the spark plug hole. Whichever method of finding TDC you decide to use, start by moving the crankshaft to the approximate TDC position. Then without rotating the crankshaft move the degree wheel so that TDC on the wheel coincides with the pointer. Next, set up your piston stops or measure piston travel on both sides of TDC. In this example I’m using a dial indicator which extends through the spark plug hole down into the cylinder. I’ve decided to take measurements at 0.050” (1.27mm) of piston travel before and after TDC. At each measurement point the number of degrees indicated on the degree wheel before and after TDC should be the same if I have found true TDC. If the degree wheel values don’t read the same before and after TDC determine which way the wheel must be rotated so that the values become equal. Then carefully rotate the degree wheel without rotating the crankshaft to alter the degree wheel’s position. Once altered, recheck and confirm that true TDC has been found. This can be a tedious process but is extremely important for checking cam timing accurately. Repeat the procedure for checking TDC 3 - 5 times to ensure repeatability and accuracy. After true TDC has been found, be extremely careful not to inadvertently move the degree wheel or pointer. Do not rotate the crankshaft using the nut securing the degree wheel to the crankshaft. Instead, use the primary drive gear nut or bolt to rotate the engine over. Next, set up a dial indicator on the intake or exhaust lifter bucket, depending on which camshaft you are checking. You’ll have to use some ingenuity here in determining the best way to secure the dial indicator to the engine. I’ve used a flat piece of steel and secured it to the cam cap using the cylinder head cover holes. Make sure the indicator travels as parallel to the path of valve travel as possible for accurate readings. Also makes sure at least 0.060” (1.52mm) of travel from the indicator’s resting position is possible so adequate valve lift can be measured. Once the indicator has been set up, the cam timing can be checked. Whenever checking timing only rotate the engine over in the direction of engine rotation. Reversing engine rotation will result in inaccurate measurements due to the reversal of gear meshes and chain slack. If you miss a measurement point, rotate the engine over until you get back to the previous position. Slowly rotate the engine over until 0.050” (1.27mm) of valve lift has occurred. Then record the position of the degree wheel. Next, rotate the engine until the cam begins to close the valve. Once only 0.050” of indicated valve lift remains record the position of the degree wheel. Repeat this process of checking opening and closing positions 3 - 5 times to check for repeatability before calculating the cam lobe center. Once you are confident in your measurements proceed to calculate the cam lobe center. On the KX250F engine my intake lobe center is as follows: Measured Intake Open (0.050” Lift) 39 ° BTDC Measured Intake Closure (0.050” Lift) 74 ° ABDC Intake Lobe Center = (( 39 + 74 + 180 ) ÷ 2 ) - 39 = 107.5° On my stock KX250F engine the actual lobe center is 107.5°. At this point if I had adjustable cam gears, I could rotate the gear slightly so that the lobe center corresponded to the specified lobe center value. The same procedure is followed for checking and adjusting the exhaust cam timing. Remember if mistakes are made when setting cam timing big problems can result, so it is best to be very patient and focused when performing this task. Always check your work 3 - 5 times to make sure the timing is repeatable and making sense. When tightening adjustable cam sprockets, use a locking agent and be sure to torque the bolts to their specified values. When working with single camshafts that have both the intake and exhaust lobes ground on them, focus your efforts on achieving correct intake timing. Correctly setting intake timing is more important since it has a larger effect on power. The intake valves also have higher lift than the exhaust valves, potentially creating clearance troubles between the piston and valve if the intake valves are mistimed. With your new fangled ability to adjust cam timing, you may be wondering what happens if you advance or retard the intake and exhaust cams from their standard positions? The lobe separation angle refers to the number of degrees which separate the lobe center of the intake lobe from the lobe center of the exhaust camshaft. The lobe separation angle can be calculated using the following formula: LSA = (Intake Centerline + Exhaust Centerline) ÷ 2 As a rule of thumb, reducing the lobe separation angle by advancing the intake and retarding the exhaust camshaft will increase valve overlap, move power further up the power curve, increase cylinder pressure, increase the chance of detonation, and reduce the piston to valve clearances. On the contrary, increasing the lobe separation angle by retarding the intake cam and advancing the exhaust cam will have somewhat of the opposite effect. There will be less valve overlap, power will move to a lower RPM, chances of detonation will be reduced, and the valve to piston clearances will increase. The likelihood of finding more or better power by advancing or retarding the camshafts is not all that likely because manufacturers, tuners, and aftermarket companies already test specific combinations of cam timings to death. In addition, if the lobe separation angle is reduced, the piston to valve clearances should be checked to ensure they are adequate. My advice is to run the prescribed cam timings to reduce the chance of problems occurring. Asymmetric camshaft timing can be set in a similar fashion to symmetric camshafts, however instead of focusing on the lobe center position, the specific opening and closing points will need to be measured. Timing cards supplied with asymmetric cams should have specific instructions for setting timing, but normally valve clearance is set to zero and cam positions are recorded at specific lift heights. Based on the measured opening and closing positions, adjustments are made to the timing until the timing matches the specified values. I hope you enjoyed this exert on checking and adjusting cam timing. As always feedback is appreciated so please leave comments below. If you're interested in more engine building info check out my book The Four Stroke Dirt Bike Engine Building Handbook. Right now we are having a 4th of July Sale where everything on our site is 20% off with the discount code fourthofjuly2017. Just be sure to enter the code upon checkout so you receive your 20% off! So if you've had your eye on our Four Stroke Dirt Bike Engine Building Handbook or even our Value Pack, but haven't pulled the trigger yet - go for it! Availabe at: DIYMotoFix.com - Paul
  18. Hello guys. Is Motul 5100 10w40 good choice for Crf's? For both engine and gearbox? Please tell me your advices!
  19. Hey all! I have a 2011 Gio X31 250cc that is losing compression gradually. It had amazing compression when it was new...but now it's becoming a tiresome task to kick-start when my electric start is down. It's burning a small amount of oil, but I don't even have to top it up between oil changes (~10 hrs. per change). I'm thinking it just needs a valve adjustment to bring the compression back up. I'm surprised how good this engine has been. I ride it hard and it keeps up with bikes 2-3x the hp and refuses to die! I don't know how to adjust the valves on a 4-stroke, let alone a Chinese one. If any of you know how to adjust the valves on a Gio X31 250cc I would appreciate the help! Do I need to pull the engine for this? Thanks
  20. So when I'm riding my '98 200M/XC nothing seems wrong until you hit the powerband in 3rd and 4th gear. It seems like the engine is hitting a rev limiter, it's going full throttle and then dies and then back to full and dies. But as soon as it gets out of 3rd and 4th and I go into 5th, 6th, 2nd, or 1st, it's perfectly fine. Does anyone know what's causing this?
  21. This noise is really bothering me. I want to know if it's something to worry about or not. I checked my valves they are in spec. Please Help!
  22. I just traded for a 2004 crf450r that has a bad crank. I am new to 4 strokes and their engines, so i am a bit scared to try to do this myself. If i were to send it to a dealership, about how much would that cost to get a crank replaced? And if i were to do it myself, would i need any specialty tools?
  23. Hey, 2 Weeks I bought a 2014 4 stroke Suzuki RMZ-250 and sometimes the bike struggles to start (hot and cold). One thing that is really strange, it's not possible to straight press down the kickstarter, I have to press to the half until the compression hits, and then back up and then Its possible to press it down. I know about the compression, which should make it easier to start the dirt bike, but here it completely blocks after the first half, its not even possible to push it down with one press. Not sure if this is normal for the 2014 model, with the 2017 model its possible to do it with one kick. As already mentioned the bike struggles to start sometimes, even when the engine is warm (this includes using choke when engine is cold and hot start when it's warm). Few days ago I've changed the oil and yesterday the gas + spark plug because the recent owner haven't used the bike for a year. I got a CR8EIA-10 spark plug, but still the bike struggles to start. There is no problem to start the bike by rolling down a hill and start it with the second gear, here everything works, but over time this is really annoying. My next guess would be to clean the air filter? But what should be my next steps, if the engine still struggles to start. Need your help guys. ~slei