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250 motor ?

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I been away from this forum for a while Now so don't flame me if this is a stupid ?

I had a freind on 05 250 x riding at the top of the power band at 12000 feet motor started to clatter then locked up. he brought it over today I tore it down to the base gasket and found the valves were serverly cup (junk) which is normal for the hours on the head, the piston hit the intakes and bent the valves, I did a piston on this bike in feb. of this year, the shirt on the piston mics out ok the rod seem ok also to motor turns over and seems ok also. I'm not why the piston hit the valves maybe it jumps the timing chain, any ideas?

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I would be sure to replace the timing chain and tensioner

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check timing chain tension. Check to see if Valve springs are week. either one of those could be the problem....If you check your timing and it is still ok then I would be looking at valve springs.

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check timing chain tension. Check to see if Valve springs are week. either one of those could be the problem....If you check your timing and it is still ok then I would be looking at valve springs.

thanks, I'll replace the chain and tensioner and do a top end with the head thanks for the info

Dave

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I would bet the springs have never been changed and were cooked long befor his ride. Then he floated the valves which hit the piston and bent them and it died. I put new springs on every year to avoid that. I think all four are about 65.00.....those springs are going up and down about 350 times a second when your ringing it out. So they tend to loose their strength after 30 or 40 hrs it seems. How many hours on his bike???

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I would bet the springs have never been changed and were cooked long befor his ride. Then he floated the valves which hit the piston and bent them and it died. I put new springs on every year to avoid that. I think all four are about 65.00.....those springs are going up and down about 350 times a second when your ringing it out. So they tend to loose their strength after 30 or 40 hrs it seems. How many hours on his bike???

alot, I'm not really sure on the hours but he's a fast B rider and always on the pipe, he had the head done a couple years ago by a guy who has done head work for me in the past and is pretty good

I'm gonna replace the chain, tensioner, piston, and redo the head I think that should take care it I hope

Thanks

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