hey guys. the flywheel in this quad sheered the bolts on the backside of the flywheel which is the reason i took it off and put a new one in. I also noticed that it had sheared the woodruff key off so i changed it. I put it back together today and it started idoled. turned it back off then went to turn it on again and just backfires. took it apart and the woodruff key was sheared off again... any suggestions or ideas what it could be?