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Showing results for tags 'valves'.
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So I recently found out the different valve clearance between 2000 yz426f and the 01-02 yz426f. I got 2002 yz426f head with valves for a great price installed and set the valves to what I've always set my valves to .15 - .20 mm intake. .25- .30 exhaust per my downloaded 2000 yz426f manual. I got a paper 2001 yz426f manual because I was tired of using phone to work on bike. So I set bike to match the cylinder head(yes it has titanium valves) and now it went starting first kick to having to bump start or not starting. Pulled plug thinking it flooded or fouled it was dry.
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Hello, hope i'm posting this properly! So my first 4 stroke rebuild was going well, so i thought! I'm trying (hard) to put my sons bike (2013 rmz 250) back together after a top end and valve service. I am having a difficult time placing the timing chain over the camshafts. Sounds silly, I know! The tensioner is removed, the engine is at top dead center on compression stroke. The chain guide appears to be installed correct and the chain goes over the exhaust cam fairly easy while pulling the chain taut with no slack down to the crank or under the crank sprocket (the video appears as if i'm allowing slack to drop to the left below the sprocket but i'm not, the guide is pressing with tension against the chain & the bottom teeth of that sprocket & holding the tension from dropping there). The marks are at 12 o'clock and 9 for the left cam and 12 & 3 for the right. None of that should really matter for slack though, the book calls for 13 pins between the top marks which i can count but I just can't loop it over the intake cam. Now maybe it's a simple mistake, and hopefully i'm missing something simple. Again my first 4T rebuild but I have tried to pay attention to detail and do things proper. I do have a manual & have followed it to a tee! For $100 its pretty vague on the subject, it just says follow the reverse order to assemble. Someone recommended I start the chain on the exhaust cam and then turn the crank to ride it up over the teeth like we all did to our bicycles as kids! The manual does not say this and it seems I would lose TDC if I did that. Is that a proper procedure? I would appreciate any tips on what I'm missing. Here are some pics at tear down and my video plea for help! Thanks in advance!
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Hi guys! I got some new valves for my XR650R and lapped them this weekend. Unfortunately, the mating surface of the exhaust valve seats have very nearly reached their service limit of 2mm, and I'm trying to find out what exactly the consequences are to have a too large contact area with the valves upon closing. The reason I'm asking is that I live in Vietnam, and I would rather not go to the machine shop and have them butcher the seats :( My guess is that the pressure of the valve springs is distributed over a larger area and then diminished, not forcing the valve to close with the same force. I'm thinking I may be better off just leaving them at the current state and sacrifice a bit of longevity? They are otherwise in good condition, as you can see below. Cheers! -
So I just took off the valve cover to check valve clearance on my new to me/for the wife 2017 kx250f. Bike looked 100% stock one notch on chain adjustment from new showroom bikes and still had the nubs on very edge of tires. The cases had some scuffs but nothing to bad, looks like no tools marks on the timing indicator or valve cover bolts just oil cap. So my question is is the marking on the camshaft holders from the factory or has someone all ready been in the head? The exhaust is at 15 and the intake is at 13mm I have no clew what the 39 means?Thanks for any input also on a side note it was kind of hard to start before changing the oil but after it fired right up so easily that I was able to start it with my hand when cycling the oil thru is that also normal? I’ll try and take a vid also it’s only 19deg out!
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I just put an fmf powerbomb on my 2006 yz250f and started it up a few times and have began to hear a slight tick in the top end. I also turned the bike over maybe 20 times without starting it to test for air leaks in the exhaust. Could this have caused too much back pressure and thrown off my valves? (the muffler plug WAS in). I know the normal 4 stroke engine noise, but this doesn't sound too normal. Could you guys take a listen and let me know? Hoping it's a normal sound. Any help appreciated! Video of sound:
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I'm COMPLETELY confused! I bought new guides and valves for my 650r. Knocked in the guides and reamed them with Honda's reamer, 07984-ZE20001, as pr shop manual. What I then find is that the exhaust valves can enter the guide tightly, but the intake cannot. I checked the numbers, and it seems to me that the new valves (14711-MBN-670 and 14721-MBN-670) are larger than they should be, but are not called OS (over-size) Here are my measurements and the standard measurements from the shop manual The reamer is 6.6, so my question is: why are the valves larger than the guide ID / reamer??? ANY help on this would be deeply appreciated! Cheers!
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Just finished adjusting the valves on my 2008 crf250r, I kicked once and the motor turned over maybe one rotation and then it locked up. I thought the cam was set correctly but it' possible its off. I also forgot to use the engine locking bolt on the bottom side that locks it at tdc while working on it but I wasn' concerned because I didn' feel like I was turning the engine the chain while working on it. Before the valve adjustment it kicked over fine. What could the issue be?
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Can anyone tell me the physical difference between a 03 & 06 head? I have a 05 and I'm looking to put a 06 on it to try and get away from the valve issues of 05. Long story but I was sent a head from a 06 and it has a hole on the right side which my 05 doesn't I then tried to put an ex valve from my 05 spares kit and it was to big to fit in the stem??? From what I can see of the parts fiche the hole has a cover (metal with a black circle) on it. Have I been ripped off and sold a 02, 03 head? I can't find much info on it but it looks like the extra hole might be for the decomp arm/lever.
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I have an 06 RMZ 250 and I wanted to know the best way to calculate the shim sizes I need because I am adjusting my valve clearances. I am new to this and people are using different formulas so I was kind of confused.
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I recently purchased a 2010 KX250F from a friend of mine that had been sitting in his garage for about 5 years. The bike seemed to be in decent shape and the price was right so i picked it up. I went through most of the bike before riding it (air filter, oil, greased all the bearings, adjusted suspension, changed all the fluids, etc) The valves sounded a bit loose so i decided to have a "Buddy of mine" adjust the valves. I get the bike back, go for a ride and the cam chain tensioner falls out while i was riding, luckily i caught it very soon after it happened and it never jumped timing. I put the tensioner back in and continue to ride the rest of the day. as the day goes on the valves sound much looser than they were originally before the adjustment was done, I decided to call it a day and tear the bike down myself. I shim the loose valves and button the bike back up, but now the thing sounds god awful. Straight up clacking coming from the right side of the top end. Since then ive probably had the bike apart and back together 4 or 5 times trying to figure out the problem. Its not the auto decompression valve, every valve is in spec, timing is solid, and the cam chain tensioner is working fine. I'm stumped. anyone have any thoughts?
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Hey all, I finally was able to start working on the my project KX250f, I think I will call it the KX Resurrection! 🙂 The previous owner did NOT take care of it...so she will get a lot of TLC and cleaning from me as it will become my main ride. When I bought the bike, it would not kickstart, and would bump start about 50% of the time. I knew it had to be either, Timing, Valves or injector clogged....and since the deal was too good to pass up on the 2014, I had to pull the trigger, The engine has been pulled and took a look at the cam timing, and it looks pretty dead on, so that is good. I then went to measure the valves and they do need some attention, ESPECIALLY the intake (hence maybe the reason why it would not start). Base on the numbers below, could I get away with re-shimming one last time before replacing the valves/seats, etc? I am going to pull the head off and take a look at the seats, etc, but I wanted to get this out there and get your input on the numbers: INTAKE (clearance: .10-.15mm): L: Measured: 0 Shim installed: 2.80mm Shim needed: 2.65mm Right intake was identical to left EXHAUST (Clearance: .17-.22mm): L: Measured: .15mm Shim Installed: 3.05mm Shim Needed: 2.98mm R: Measure: .15mm Shim installed: 3.10mm Shim Needed: 3.03mm Thanks for your input.
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Just tightened my valve lash to spec after having terrible clacking noise when idling. It would start before when cold with no choke at all but would click and clack when idling. But now, with the correct valve adjustment, the engine does not want to start. It will backfire and damn near break my foot so I know that it is definitely getting fuel. What is the best way to adjust the carburetors on these bikes? I know there is the large screw on the right side to adjust both of the slides for idle speed, but where is the air-fuel mixture screw on the carbs? I suspect this is my issue now that the valve lash is adjusted correctly. Any info or advice would be greatly appreciated.
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Hey guys, we can really use some know-how on this issue, thank you in advance for any help you can provide! We've been struggling for a few weeks with a kickstart issue with a 2013 KX250F. My son purchased the bike grenaded; broken valves, damaged head, bad piston and cylinder (piston jammed sideways in cylinder), bad crank and rod, bad bearings, and all the other issues that go along with these. We sent the head to Millennium for repair and we also had them install Kibblewhite black diamond valves and springs. We installed a new crank, crank bearings, a few other bad bearings, new cam chain, Cylinder Works cylinder, Vertex piston, gaskets, and reworked head. We shimmed the valves and checked them a few times with the new springs - we ended up make a small change in one of the exhaust shims and they are all now within factory spec - 0.10-0.15mm intake and 0.17-0.22mm exhaust. The bike did sit for over a year with fuel in it, but we emptied it and put in rec gas (90 octane without ethanol) along with seafoam and some injector cleaner. We have just over 60 pounds of compression when we tested it. With all that said, we can not get the bike to kick start. We can kick it until our leg falls off and she won't start. Now, if we push it and it turns over once or twice and doesn't start then we are able to kick start it. If we spray starting fluid in the throttle body it will also kick start. We tested the capacitor and it seems to check out. We're not sure if it could be an issue with the fuel pump, although once it's running it runs great. We push started it up until now and we've run it on a trail system for a few hours without any issue. The fuel injection works great without any hesitation so it seems that the injectors and fuel pump are good. Once we shut it off it will kick start within a few minutes just like it should. If it cools down for about 15 minutes then it won't kick start again. When we pulled the tank off we did notice that the gas leaks out of the fuel pump and never stops leaking out. When we apply 12 volts to the fuel pump in testing it sprays fuel quite well. As I said before, once started it runs great and everything works as it should. We have a little over 2 hours on it and she's still running strong. We are out of ideas as to what the issue could be and any help here would be greatly appreciated! Thanks for the great community! Rich and Josh
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Hey guys so I’m going to start off by saying I’m not very mechanically informed on 4 stroke motorcycles. I bought my first 4 stroke about two years ago, bike mostly sits it’s always started 1st-3rd kick and ran beautifully. I logged about 40 hours on it and brought it into a local shop for a valve adjustment. When they gave it back to me it now takes about 20 kicks to start and it even now backfires occasionally, Slight loss of compression.. they claim they messed around with the idle screw so much to adjust it accordingly but still it takes forever to get running. I was told these bikes have some electrical issues with the spark plug cap staying on, so I checked for spark, all good, cap was on fine and I had spark on a new spark plug. Still however it’s taking forever to start. Two questions, has anyone else had similar issues? and does that idle screw allow more air/fuel to enter the bike and which direction should i turn the screw to make proper adjustments?
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I got a 2014 Kx250f and it started sputtering the other day when it gets hot and cutting off and it would start back up if you pull the clutch in and bump start it. Once the bike cools down, it will start fine and run fine. Any ideas what this could be? Considered checking valves, but runs fine until it gets hot. -
Buckle in this is a long one. Any advice is appreciated! I have a 2011 RMZ 250 that has done me very well for 4 years. Has been a very reliable bike with lots of power. Last year it started to act up a bit, slightly less power & became more difficult to start, especially cold (side note: it’s a Suzuki so it’s never started great cold but usually 3 or 4th kick was the case). Still ran okay though & fiddled with the fuel screw a bit which seemed to help with the starting/power issue for the rest of the season. This past winter we pulled it apart, put a brand new piston in, checked the valve clearances, moderate amount of carbon build up on the valves which we cleaned off, and put in a new spark plug which is also in spec. Bike still wouldn’t start great cold but was starting on about the 8-10th kick and power seemed to be improved although not 100%. I’ve take it for quite a few rides now and broken the new piston in and am having more issues: -won’t kick over cold at all but bump starts just fine -will kick over first or 2nd kick when warm but NOT when the bike starts to get even slightly hot -very little top end power. Bottom of the gears seem to be full power and the hotter the bike gets the less power I have in the top end -bike began to backfire quiet a bit when hot -won’t idle in gear when hot Any advice on what to replace/trouble shoot next? I had a buddy tell me it could be a worn out injector so that’s what I’m looking at replacing next. Thanks!
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Can someone tell me the manufacture specifications for valve clearances on a 2002 yz250f??!? I’ve looked some up and seen some videos but the more information the merrier right?? The manual I ordered hasn’t been delivered yet....
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I have a project XR100 I've had for a while and never got around to working on, but here I am now. I rode it for about an hour and noticed it was running too rich up top and too lean down low and would also shut off when it got hot. So, I changed the jets from a 38 pilot and 105 main to a 40 pilot and 100 main. Runs great when cold/warm, but still dies when hot. VALVE CLEARANCES duh!!!! In short, after rejetting this bike a few times to get the perfect mixture with my valves out of wack (did not know at the time), will I end up rejetting again once the valves are set to spec or should my new tune still be fine despite the change in valve clearance? Adjusting the valves this afternoon, and just want to be ready to take the carb back off if this ends up being a necessary concern.
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So the bike was running like crap, bogging, not starting, not idling so I got the carburetor cleaned and jetted. Then I got it back and the same problems. The dude said it wasn’t the carb. And as of yesterday it won’t crank. It will try but it won’t crank. Is it the valves. If the valves are bad wouldn’t it still crank. Any help would be much appreciated. thanks
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Recently changed the cams to hotcams without checking the valve lash like an idiot. Went to change the shims and couldn’t get one of the barrels back on. Looks like This. What’s my best option? Buy the oem pieces for this one valve or buy a whole new forged set?
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Hey guys! Im gonna start out with posting all the information i think is needed for you guys to help me with this problem! Stock engine 2007 crf250r. Valve clearances are good and have JUST been shimmed with a double and triple check. Jetting is 175 main, stock needle position, 45 pilot and 50 leak jet. 1000ft above sea level. Im still having a terrible time starting and it used to be a 1 kick bike. I haven't changed my kick routine at all. 3 slow kicks, 3 throttle twist and then kick. Will sometimes start if i give it some gas when kicking. And then it starts 1-4 kicks after its warm. Im lost and dont know what else to look for. Thanks! -
This has been an ongoing issue, as I am sure some of you are beginning to notice.. sorry for the somewhat repetitive posts in advance. My valves were out of spec, I was only getting 85-90 PSI of compression. I shimmed my valves to the correct clearance, and I got the compression up to 150 psi. Now after riding my bike for 15-20 minutes, it will start doing the same thing it did before - it will idle super low and eventually bog out. I had the idle adjustment turned up very high, when I gave it a little throttle the idle would kick up for a couple seconds, then it would settle back down to extremely low and bog out. To me this sounds like something with the idle air circ, or jetting. Could something with the valves cause this as well? Want to get a second opinion before I send the head in for the $500 rebuild and still have the same issue. Thank you all again!
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I've been doing research over week now. Bought a 04 crf250r for $900 on terms it needed a cam chain. Come to find out the cam chain tension failed and the chain was shot. However there was a surprise. the left cam lobe closes to the cam wheel (in the head) destroyed the heads housing around the valve. Yes destroyed. Chucks of metal were found and the cap above the valve (under the cam lobe) was also destroyed and chewed up. The bike did run before i opened it decently well but did make noise (2nd 3rd kick). I didn't want to blow it up so i torn it apart. Now i have a new cam chain and tension valve cover gasket and flywheel stator (left side engine gasket) also new head is on its way. PROBLEM- Guys at the motorsports store said valves looked good and jug looked fine along with the piston (valves were still in head and he just glanced at them). QUESTION-Do i reuse the old valves in my new head (probably not) so if i order new valves can i use the old springs with the new valves? Last question, since ill have a new head and (if need be valves,springs,locks,seals) what size shim (referring to the small metal circles under the lifters) do i use since it'll be OEM. Please get back with me asap. Thank you!!
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Hey guys, pretty knew to forum i have a 2000 klx300r. Recently started making a fapping sound on top end coming from timing chain side. Checked valve clearance and are in spec. I was thinking the sound was either valves, decomp, timing chain and or guides, tensioner. Hopefully not piston
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Hello everyone. So I'm stuck...I have done rebuilds before and never seen this...I'm by no means a pro. I did a piston and ring install, rockers, and it all went well. Line up TDC, put on head cover and go to check rockers for a little play...exhaust valve has it, intake doesn't...tried 9 times making sure it's even and same result. As soon as bolts get to about 5lbs or less...prob less the rocker won't budge. Is this normal...I should have free play if I'm at TDC on compression stroke...thanks
