Well I am about to tear my heads off and see if I can see anything wrong on the top end maybe before I go into the bottom end after my super exciting Friday. I was wondering..if my lower end had screwed up wouldn't it have kept running and just started making alot of noise. It shut down on me, and started making a knocking sound after falling flat on its face. I didn't even try to start it until I got home. The cop that had caught us said he thought maybe it was the cdi box. When I changed it out, before I tried to start it with the old one ...it backfired like hell but cranked right up. It sounds very weak and making a knocking noise. I started it briefly again yesterday and the same serious bad backfiring. Could I have blown a head gasket or something in the top end, dropped a valve? It also has a funky smell....I know you guys are awesome, and can just maybe tell me what to do or look for before I just start tearing things apart! I am in big time trouble with the boss and she is not going to go for me spending all kinds of money again right here before christmas.