i jsut got done open it up like 1st trow 5th.. so maybe i leaned it out.. idk.it just lost all power and i pulled in the clutch and tried keeping it running but it wouldn't... and it sounded like metal grinding inside so i shut it down and pushed it home.. i pulled the head off and it looks great inside.. so maybe i just overheated it??? i was riding for 3-4 hours non stop..or it could be in my clutch side of the motor.. im going ot pull it apart tomorrow see whats going on it there..