Just rebuild a 400 sport, it starts up good but after warmup the engine continues to rev high after i let off the throttle. The oil to fuel ratio is rich but I am unsure of the fuel/air mixture. No air leaks that i can see. Anyone know why it is doing this. The Throttle is not sticking but it seems like it is.

 

sounds like what my blaster does, it runs great until it gets warmed up then it revvs for the moon.. I think with my wheeler at least, it is the air/fuel screw on the carb is messed up, and I am missing my idle screw. Havent really had a problem with it, but mine is also a standard... Ive ran it for the past week like that and so far havent blow it up.. lucky I guess.. try turning the screw on the left side of the carb, the one without a spring... works a little for the blaster, but cuz Im missing the other screw it only works a little.. anyways.. good luck!