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Im dealing with a 07 150r that locked up right before leaving the take off of a jump. The bike recently had a pro-x piston installed in it. When tearing down the engine we found several problems. first an intake bucket stuck in the bore and broke the cam carrier (i assume this is what locked the bike up). Cam chain guide (not tensioner side) was melted and deformed. last the intake valves were hitting the piston.



I found that the triangle on the piston was pointing towards the intake. Please correct me if im wrong but i believe the triangle is supposed to face the exhaust? I know oem pistons have an IN mark on them.



Besided the valves hitting the pison the piston and crank check out ok.



Motor had oil in it and was changed regular. this is a race bike.



Any help would be greatly appreciated.
 

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yeah the arrow on the piston definetly faces the exhaust, if it melted the cam chain guide that thing got really hot, never really seen one melt before, what does the camshaft lobes look like, it really sound like it could be maybe a couple of different things, i would guess maybe the engine was over revved possibly racing and actually broke the valve and the valve got jammed in the bore ( this happened to a friend of mine at budds creek) or possibly it jumped timing, or an oil pump failure, thats my suggestions, good luck racing, hope ya get back out there soon:D
 
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