My buddy has a big bear 400 that is spitting back through the carb at idle and just above idle. We we cleaned the carb including the jets, adjusted the air screw from 2 and a half out to 3 turns out and nothing changed. Could it be the idle jet id clogged again some how? It pushes the carb out of the intake hose after it spits back 4 or 5 times. Any help would be appreciated..

 

Anyone? Bueller..

 

Just a thought, check your valve lash, maybe you are getting a little leakage back from the motor through a poor sealing or late closing valve, and that could be causing the back fire problem. Make sure your cam timing is also correct, when at TDC, the mark on the cam sprocket should line up with the mark on the head casing.

 

I will give the valves a try, Hope it works..