I have a 2003 660 raptor that won't start. Last drive I tried to start it and just the starter spun but not the engine. The fly wheel nut was loose I tightened that then motor would turn over but still not start. Cleaned carbs set valves it has good spark. Eventually got it too run temporarily. Now every time I try and start it back fires very loudly when given gas I can't figure this out

 

Found the problem. The woodruff key sheared off and was out of time