KX Riders
Maintenance & Technical => KX450F / KX250F => Topic started by: ThrottleJunky on April 27, 2011, 12:29:29 PM
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I stalled my bike in a turn and couldn't get it restarted. I thought I flooded it while trying. Took it home and tried to start it again but couldn't get it to fire off. Checked all vital signs and found the timing off a small amount. Timing kept moving so removed the flywheel and found the woodruff key sheared.
Anybody ever heard of the 450's shearing keys and why?
Thanks!
TJ
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TJ,
Although I haven't spent a whole lot of time with newer 4 strokes, the 500's have a reputation for snapping them.
Why they snap may have to do with the fit of the tapers of the flywheel and crank.
The only remedy I read about was to lap the two mating surfaces.
I used valve lapping compound and lapped the flywheel to the crank. I didn't get crazy, maybe 5 min. Turn by hand back and forth. The idea is to get the High/low spots out. Clean everything well before reinstalling.
Tuck\o/
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+ 1 this works well, listen to tucko he know his stuff :-D
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Thanks for the info!
I did a light prussian blue check to be sure the taper contact was good before installation. I read about 90%. I will put a light lap on it before reassembly.
I haven't sheared a key in a flywheel since the early 70's! I had about 15 total minutes on this engine.
Back when I was building this bike a 9 oz. Stealthy flywheel weight popped up on Ebay and I couldn't resist. I'm thinking about the effect of the extra weights' inertia has upon stalling the engine. This may have something to do with it.
I ordered 3 keys so if it happens again with the flywheel weight, it will be coming off!