4 strokes are not impossible to seize. I seized my 360 at the end of the back straight at Mosport. It freed up fairly easily and I ran it later that day. Scuffed the piston more than the bore. I also seized the BSA 250 at the same place. Destroyed that piston and messed the bore up pretty good too. I think the ignition pickup slipped in the cam.
Mike O.
Mike O.