well i can tell you all something, my fuel tank is fine there is nothing wrong with it, there is a new fuel tank, there is nothing wrong with the clutch, and there is also nothing wrong with the bearings on the crank or anything to do with the motor. the motor turns over with a hard spot at the top like it should. my personal opinion is i think that the piston sleeve is to wide at the very bottom of the stroke so it is creating blow by. thats my opinion. i think aslo it might be the carb but i have returned everything to factory settings and the motor is stock.