That "seat pop" is a back fire and WATCH OUT for your AIRBOX...THAT back fire is what BLEW UP my airbox...DEF look into TBS needles (Benny your right) they eliminated the bad flat spot I had and are a simple, cheap fix...3-1/4 sounds about right + - 1/4-1/2 turn and remember both carbs MIGHT not be the SAME # of turns...then SYNC your carbs when your done!
