[xeon]

The addition of a free flowing exhaust and filter along with a jet kit bring up all sorts of variables. Did it ever run "right" for you? It is possible the jetting could use some work.

I'm not sure what the nature of your problem is exactly from your description, but does it have an erratic idle? If so, it would lead me to want to clean the carbs and sync them along with inspecting the plugs... no harm in just replacing them anyway. Another thing that can give you erratic throttle response could be a tank of bad gas.