my 1988 blaster keeps backfiring while i'm riding. it starts just fine but when i am riding and everytime i give it gas it either bogs down to low rpm and sputters or it backfires rapidly. it wont go to high rpm cause it keeps backfiring the only aftermarket piece it has is the silencer which is an fmf. i want to say powercore 2 but there is no sticker so i cant tell.