ok, i got the valve timing on the problem was that the guy had it 180 out and the cam gear on backwards. So now my v alve timing is bang on, i cleaned the carb and adjusted the valves. When i kick it over it backfires and just about tears my leg off. It will not start and run. The only thing i noticed is there is some slack in the timing chain but im not sure, you would think it would start at least. Is it maybe an ignition thing ( i have good spark by the way), and if it is ignition timing how do i check it, im new to the small engines in case you didnt notice, but i want to be able to ride this thing. Please help. Thanks!!!!!!