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2003 yzf250 engine problem HELP!

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My 03 yzf250 will start fine for the most part but as soon as it gets warm it locks up, like the bottom end seized. But after it cools down it will free itself up... Anyone have any idea why it would do that. The only thing I've done lately is replace the piston and I know it needs a stater because the inside of the flywheel was all eatin' up from what looks to be, from the stater swelling. Do you think that would be whats causing it... I already have anew flywheel and stater but if theres a deeper problem i would like to do everything at once... 

 

Any feedback would be great, Thanks.

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Usually when I see a flywheel chewed up something else has gone wrong and the flywheel just attracts the debris. One thing I would check is the cam caps. Since you've recently had that apart to replace the piston that is a possible area if they were over torqued. Cam cap debris would be aluminum and non magnetic so there might be something else also going on. Clay

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Possible but when I did the top end I shimmed the valves to specs, new springs and seals,new timing chain, caps have no sign of wear. Everything was torqued to spec with a torque wrench to 40flbs on the head and 8flbs on cams. The bike ran great for 4 days after that and then i was in the frail and it just locked up no lose of power before hand or bog just dead lock. now it will start but after about 5 min it will lock...

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I'd pull the filter next. Take a knife and cut the paper out then spread it out and see what's in it. Check it with a magnet. If it's full of magnetic material my next guess would be connecting rod bearing especially if it's the original crankshaft. Clay

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