My experience is that all around performance from the stock pumper carbs is excellent once they are properly functioning and then tuned correctly. The biggest thing that I have learned with carb tuning is that you are absolutely, completely, utterly wasting your time swapping main jets, adjusting needle clip postion etc, until you actually have your carbs (and the rest of the bikes systems for that matter) functioning properly first. Clean pilots and idle passages, floats that seal and are adjusted correctly (can be observed in real time with clear tubing on the over flow nubs on these carbs,) adjustment and confirmed proper function of the accelerator pump, air tight intake connections, carb synch set initially on the bench and finished properly on the running bike with guages etc etc etc. . . . Although it is possible that the performance problems described in the inital post can be attributed to improper main jet size or needle position, I would guess that there is a more fundamental issue with the carbs basic function. Fix what ails em first and then tuning should be doable.
