XR200R - Hole in Piston

[TRX250X]

My brother just got a 2000 xr200r this summer. He was riding it last week back to the woods to go hunting. It acted fine and he wasn't riding hard. When he fired it up to go home, it wouldn't start. He pushed it a half mile, then walked to get dad to get his Prairie 400 to pull it the rest of the way down the road. They tried starting it while pulling it. It didn't do anything. They took it home and messed with it some, it acted like was firing, so they tried pulling it again, I guess my brother heard a clank or something from the engine.

They pulled it apart and found a broken valve (not sure which one) but it was broken off, and a hole in the piston.

The cam chain and sprockets for it look decent. Any ideas on what could have caused this?

[mojoe2878]

it still may have stretched enough and jumped time even though the chain appears to look ok. the tensioner may have given out also letting slack in the chain.
also the valve may have broken and dropped slightly at first just enough so it wouldnt build up enough compression to start, then when pulling it it finally dislodged dropped down enough to hit the piston.
hope the head and valve seats werent damaged too bad.
best thing to do is go ahead and replace the gears and chain when ya'll rebuild.

[TRX250X]

Thanks,

surprisingly everything else in the motor looked fine, even the tensioner. I looked up some parts for him. I told dad they better just replace the chain and stuff while they had it apart.