My 4 stroke 49.5cc manual trans backfires when I release the throttle. I'll shift normally through to 4th gear, then when I need to slow down, I release or back off the throttle and WHACK! a nice big fat pop. No other backfiring except when I back off the throttle. The only way to avoid it seems to be if I engage the clutch immediately as I'm backing off the throttle. I've played with the mixture a bit, but that doesn't seem to help. Any advice???
Gary