I've been having this backfiring and bogging issue, It only happens under heavy throtle, like from a stand still if i go full throttle it will accelerate to about mid speed and then backfire and bog, if i ease into the throttle everythings fine, I've tried leaning and richening the HSN but to no avail, the engine is a .21 vertex with about a gallon through it, kinda stumped any help would be great thanks guys