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piston/valve interference

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i am rebuilding a 07 crf150r for a friend where i replaced valves with kibblewhite and piston/rings with wisco. upon reassembly when setting cam timing on marks, piston hits intake valves as you turn motor and valve start to open. i can retard timing by one link in chain and everything clears. any ideas? thanks -jamie

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i have tried it both ways. i finally just set it with cam retarted one tooth on sprocket which put timing marks on cam near 1 oclock and 7 oclock. bike fired right up. i havent complete got it back together yet to ride it but it starts right up. i never lined up marks before i tore down, so maybe it was like this from the start. it sure has made my head hurt. -jamie

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Did line the cam mark up with mark on cam housing or did you just line up cam gear. also have you reshimed hope this helps.

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hi jamdrz.

my last post should of said did you.

sorry.

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Are you 100% sure you didn't put the piston in backwards? If so the valves will hit the piston cause the valve reliefs on top of the piston are usally bigger for the intakes.

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Are you 100% sure you didn't put the piston in backwards? If so the valves will hit the piston cause the valve reliefs on top of the piston are usally bigger for the intakes.

well i was 99% sure i installed piston correctly but that was the only thing i changed that could cause interference so i tore back down and sure enough i did install piston correctly. so i reassembled and set timing at one link retarded on cam and bike runs great. the cam has to be off. this bike has supposedly had recall done. its the craziest thing i have saw in a while. i rode bike about 30 min and it ran like raped ape, pulled valve cover and rechecked valves and still set at .006 and .010, so he should be good to go. -jamie

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Beware! I've had a cam slip. The gear is pressed on.Mine slipped when the failure occured before rebuilding. What happened and at what rpm, high or low before the fix? If it has slipped I would thinl it will prob. do it again. W/ stock springs, these can hit valves on high rpm, but usually only when in the air. W/ no engine load, the engine revs so quick that the engine is still speeding up b4 rev limiter kicks in. Slipping bad but better than catastophic failure. I dont know how to fix it yet though. we had another cam, so just ran it.

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Beware! I've had a cam slip. The gear is pressed on.Mine slipped when the failure occured before rebuilding. What happened and at what rpm, high or low before the fix? If it has slipped I would thinl it will prob. do it again. W/ stock springs, these can hit valves on high rpm, but usually only when in the air. W/ no engine load, the engine revs so quick that the engine is still speeding up b4 rev limiter kicks in. Slipping bad but better than catastophic failure. I dont know how to fix it yet though. we had another cam, so just ran it.

Yep, I've had this happen on some bikes... very rare though.

I do weld some sprockets on sometimes... just in a couple spots. (in the 150 case... you'd weld the hub only)

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Beware! I've had a cam slip. The gear is pressed on.Mine slipped when the failure occured before rebuilding. What happened and at what rpm, high or low before the fix? If it has slipped I would thinl it will prob. do it again. W/ stock springs, these can hit valves on high rpm, but usually only when in the air. W/ no engine load, the engine revs so quick that the engine is still speeding up b4 rev limiter kicks in. Slipping bad but better than catastophic failure. I dont know how to fix it yet though. we had another cam, so just ran it.

that might explain it. he bought this bike used and hadnt had it long when it developed a peck in the motor. sounded to be on rt side but sounded similar to timing chain noise. at that time i cked valves for 1st time and the rt intake was below 0. i thought it probably had hit piston then. i adjusted all valves and it ran fine, still had noise. that was probably 6 monthes ago and several valve adjustment since. there was no sign of piston/valve interference when i tore motor down other than both intakes were real shiny on flat other edge on top of valve where it goes into recess in piston top. the noise seems to be gone now with new piston and valves and timing set one link retarded on cam. i think i will suggest a new cam before he rides this bike much. any suggestions on cams.... hotcams etc. thanks -jamie

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I've had both hotcams stage 1 and a crower cam that was supposed to be better. We could tell no difference in the bikes at all, I say save some money and go w/ hotcam. I just meant that I did'nt know how to degree the cam back in right, well, I know how, just need specs. I am fearful of the idea that we also had to weld, when ours hit anyway, we barely hit, it hurt nothing at all, what however would have happened if it were welded solid and couldn't spin the cam? Thats right, really scary catastrophic stuff we don't even want to talk about!! I'd be very nervous to ride that thing, if it has slipped, did the gear scoot off a little bit, and is now looser? Not tryin to scare you, just hate to see something worse happen. Check this out man, ours had this noise much as you describe, we tore it down, found nothing, valve lash all good, put it back together, and still had the noise! We were freakin out! Took it back apart, hours of studying on it later, discovered what it was, if I hadn't just have known where the lobes should be in certain parts of the stroke, I dont know if we would ever had figured it out! This happened w/ the crower cam. Danny Crower says (and I believe him) that he doesn't mess w/ that part, I mean we sent him a stock cam to regrind, the issue for me though is that the kid has been back to the same track and gotten faster and is now riding much more aggressively, yet still we have had no problems like this w/ the hotcam. I'm definately not blaming the Crower regrind, I'm just telling you what I know.

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Beware! I've had a cam slip. The gear is pressed on.

wrenchard01 if talk about crankshalf cam gear that is pressed on? then it alway a good idea to change out the half moon keyway they can shear.

I'm guesting that it not soild cut on the crankshalf it self which haven't gotting that far in to the motor

jamdrz I was doing my valve clearance adjustment which I final had time for it this weekend after doing a big V8 swap on a S10 Blazer boy what fun that was and yes the timing on marks on crank flywheel is off if that what you are looking at which is for ignition timing when using a timing ligth when you should be look at the rigth side crank case after take off rigth side crankshaft hole capo-ring you should see punch mark on the primary drive gear which should line up with crank case index mark or is it also off?.

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Hey I have the same type of issue. My bike already had the recall preformed. The motor started a clicking noise. When I checked it out I found the cam timing was off. In fact the exhaust valves were hitting the piston. I tore the motor apart and found the intake and exhaust valves had been hitting the piston. This was strange. I rebuilt the motor and before finishing assembly, I turned the motor over. That was when I found out the piston was hitting the valves. I looked it over carefully, I did as you stated and moved the chain one link to get the motor to turn over. I did not like that fix so I purchased a Hot cam stage 1. I installed it and the bike ran great. Then one month later the same thing happened. The valves are hitting the piston again. To me the cam design has a major flaw. The cam is made, then they install the bearing and then press on a flange. This is what is spinning and throwing the timing of the cam off. I called Hot cams and they stated to send it in. I have. I am interested to see what they think. If I am understanding right do some people weld the cam gear and the cam together to solve this problem? I can see where that would work but not very interested in doing that.

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if the kibble steel valves are thicker on the margiin it might hit the piston. they may protrude further out and touch somewhere , or your cam slipped. if it runs like crap in the retarded position you know there's something wrong with those valves thickness and you need to put the cam back in std. position.

5150 you said after we reground your megacycle last year it was better than anything you had ever tried ? , remember when you came to my shop , the megacycle had so much lift it broke your cam housing !!! and i hooked you up big time...thanks for nothing. you forget who helped you out? !!!

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quadcart that might explain it that honda didn't add any kind dowe pin or key way or it weak pin to hold 2 paces cam in place so that maybe why some people are welding the cam gear and the cam together to solve this problem

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if the kibble steel valves are thicker on the margiin it might hit the piston. they may protrude further out and touch somewhere , or your cam slipped. if it runs like crap in the retarded position you know there's something wrong with those valves thickness and you need to put the cam back in std. position.

5150 you said after we reground your megacycle last year it was better than anything you had ever tried ? , remember when you came to my shop , the megacycle had so much lift it broke your cam housing !!! and i hooked you up big time...thanks for nothing. you forget who helped you out? !!![

SORRY YOU ARE CORRECT I USED THE MEGACYLE BILLET CAM REGROUND BY CROWER AND THAT IS THE CAM WE RUN

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