My 450 was running good then I went to ride the next day and when I would try to accelerate fast it bogs. I cant go into high speeds at all, It will barely even go and just sit there and bog down to where it almost dies or does die. I have also noticed that it backfires a lot and spits flames every now and then. The exhaust blows white smoke but its not oil burning it just smells like gas. The only thing aftermarket on it is White Brothers Exhaust as I know of. Someone help me please.