Having run an OPS.. which looks exacly identical to that engine except the porting is modded on that.. DUMP that carb! the idle screw broke in half on mine and the broken piece stuck in the carb barrel wide open. I found a replacement and the same thing happened again! After that I threw a hyper .21 carb on it and have not had aproblem since. OPS's are good engines imo.. mine flies andhas lasted a hell of a long time.