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superneon135

R.i.p 426

14 posts in this topic

ok i got my 2000 yzf 426 this past winter. well about 3 races into this season a valve went into the piston and the scuffed the head, no big deal had the head redone all new valves and new athena piston kit with gasket kit. well about 3 more races later same thing so i got new wisco piston kit with gaskets, new valves, new head, new hot cam. well the racing season was going great got me into 3rd place for the championship, the otherday i desided to take it to the dunes for some rideing with my dad, about 5 min after rideing blew it up again. when i got it apart again same dam thing :thumbsup: i just dont understand what im doing wrong i followed specs and every thing. i love the bike when it runs but after putting all the money into it over and over i just want to get rid of it, can anyone help and maybe give me some ideas what may be wrong. also does any one have a head for sale lol i need one

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sounds like you need a new bike to me...your 426 will just turn out to be a bigger money pit than it is already

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sounds like you need a new bike to me...your 426 will just turn out to be a bigger money pit than it is already

Yeah it does seem strange. The same failure three times. It is a kind of old bike now. I hope you can afford to get a new one. A nice aluminium frame will take your mind off your troubles..

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Did you replace the springs when you replaced the valves as well?

i was thinking the same thing.

what did you reuse between the two heads? did you reuse the springs? did you measure the installed height of the valve? (probly not, but i would have after the second time..)

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sounds like you need a new bike to me...your 426 will just turn out to be a bigger money pit than it is already

LMAO !!! :thumbsup: I think Zique and MR. Dude are on it!

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i replaced every thing but the stock ehaust cam in the head after the first time i even installed the hot cam after the first time, the second i also replaced every thing but the cams again and the timing chain, i even called the parts shop and got the specs again thinking the told me wrong the first time or i miss understood. the only thing i could find in the bottom of the motor was the water pump shaft was hard to turn by hand could this be the problem???

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ok i got my 2000 yzf 426 this past winter. well about 3 races into this season a valve went into the piston and the scuffed the head, no big deal had the head redone all new valves and new athena piston kit with gasket kit. well about 3 more races later same thing so i got new wisco piston kit with gaskets, new valves, new head, new hot cam. well the racing season was going great got me into 3rd place for the championship, the otherday i desided to take it to the dunes for some rideing with my dad, about 5 min after rideing blew it up again. when i got it apart again same dam thing :thumbsup: i just dont understand what im doing wrong i followed specs and every thing. i love the bike when it runs but after putting all the money into it over and over i just want to get rid of it, can anyone help and maybe give me some ideas what may be wrong. also does any one have a head for sale lol i need one

If you had 3 different valves hit the piston on 3 different occasions, it sounds to me like your cam chain keeps jumping a tooth, throwing off your timing. Check your cam chain tensioner, and see if it's extremely worn. Even if it isn't, replace it anyways, along with cam chain and sprocket. Chains stretch over time.

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...it sounds to me like your cam chain keeps jumping a tooth, throwing off your timing.
Crank sprocket.

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What I meant was, check the crank sprocket for being excessively worn.

Ah, I see. Can this be done without him splitting the cases?

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Not unless you know how to replace the crankshaft without splitting the cases. :thumbsup: The sprocket is cut directly on the crank.

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