Maintenance & Technical > KX450F / KX250F

10 hour motor with a super tight exhaust valve

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JEREMYZDEAD:
Just got a motor with 10 hours on it. It has way more power than my old motor but has some noise coming out the valve train when 1/8 throttle to a little more. It's also hard to start and kinda souded like the valve was hitting the piston on lower rpms. Checked the valves and one is so tight that the smallest feeler gauge won't past under it at tdc. Has anyone bent avalve or needed to reshim at such an early life span of a motor. It's an 06 with 9.7 hours on it.

don46:
First, yes it is probably more common to shim at an early stage rather than later, as the valves seat in they get tighter and may need to be shimmed. If you continue to ride like it is you'll need another new motor. Change the piston to an aftermarket, I like  Wiesco, the 06 had an issue with the piston breaking. Tight vavle is probably why it doesn't want to start. Remember when your selling something you can say whatever you want to, who's going to challenge you, an 06 with 10 hours, hmmmm, pretty tough to swallow. maybe 10 hours since the person put an hour meter on it.

JEREMYZDEAD:
Theres a wiseco already in it. So I'll try to just get the valves shimmed. But I swear I heard contact of the valves, if it runs after the noise then I have a chance of it not being bent?

don46:
motor only has 10hrs. but they installed a wiesco hmmm.

So why do you think a valve is bent? to little clearance should not hit the piston, it wouldn't start if a valve is open and there is only .0045 to .008 clearance from low to high and intake to exhaust  so I'd be suprised it a valve is hitting the piston.

maddoggy:
i agree with don on this deal. a 10hr motor that has been gone through enough to have a weisco piston in it? highly doubtful that the motor sits at 10 hours. my guess is that the motor is high hours and the valve seats are shot and that is why your valve clearance is zero. i see this alot in the new caterpillar acert engines when they get towards 3/4 life. the noise you are hearing is probably something else in the engine that is broke or worn out and slapping. i hope we are wrong and everything turns out ok.

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