I have a very very strong running high revving 31cc bolans bl100 engine it starts very easy also. The nut holding the flywheel tight to the crank was a press fit inside the pulley. The nut was also flush welded to the pulley. Then the pulley just screws right onto the crank to hold the flywheel tight. Welded the starter dogs to the pulley also. Now I'm trying to figure out an in frame mount and I'll be using a kids bike rim as a rear tire pulley. Anyone ever have luck with belt drive?