I just picked up a '99 yz80 and the engine is DONE. I'm have in trouble finding a motor, but not yz85 motors. Does anyone know if the 85cc motor will fit in the yz80's frame without modifications?
probably not without a few minor modifications. Your best bet would be to go to your local yamaha dealer and compare part numbers in the microfiche (the frames, the swingarms, whatnot)