KX Riders
Maintenance & Technical => KX450F / KX250F => Topic started by: JEREMYZDEAD on May 02, 2010, 06:06:55 PM
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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.
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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.
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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?
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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.
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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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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.
As Don stated above, piston problems. What if it's the piston making the noise? How do you KNOW the piston has been changed? The seller said so? I am no expert on these (or anything else) but I have never seen a valve tighten up like that in just 10 hours use. Sounds like you should not assume anything until you investigate further.
Just my $.02 worth, hope everything works out.
DoldGuy
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I took the guys word on the motor. You may know him as toomanykawis. Cool guy, I trust him. Well I took it apart today and the shim popped out from where it sits ontop of ths valv locks and wedged itself between the top of the retainer washer and cup. Which brought it out of spec. Put it back together an it was .10 over so I reshimmed and now it runs like it did when I first put it in. The mech here says its from over rev. I don't know. Thanks anyway.
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there are alot of times that i hope we are wrong when we give our opinion. i hope everything turns out this good. i would trust 99.9% of the guys on here to sell parts and not screw another member. go ride and keep those revs under 50,000. :-D
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It was .07 over and I like to give the benefit of the doubt with ebay insurance. :-D
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It was my motor. It had less than ten hours on it. I put a Wiseco in cause with 06's so many said they had piston failures and it destroyed the engine. Do you hold the throttle open in the air over jumps a lot? Engine has a rev limiter but even so bouncing off it enough could float the valves and have a shim get wedged.
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I rev it to bring it down from ajump... could have been in a wrong gear on the whoops too. I don't remember hitting the limiter on the bike. That motor just pulls. I would know I've hit it a bunch of times on my old motor.
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I don't recall panic reving the motor. I did a total 15 min. trail and 10 min at the most track...out of shape!