The problem I have is when I let off the gas it has poping sound.I have cleaned carbs, checked valve clearance.It does have a supertrap slipon with five plate set up and a k+n filter.It ran really good(a few days) and it started this and has just gotten worse. The top end has gotten worse to. Could it be an exhast valve problem or maybe exhast leak? Or a carb problem. Would a 1983 600tt carb work on this bike?