Are the carb. vacuum pistons supposed to all open when the bike is reved through the rpm range???? #4 carb. vacuum piston is the only one opening up. This 1993 vfr 750 hasn't run strong since it was put back together after 12 years of down time.It doesn't miss,skip or run rough,just week throgh the rpm range. It has a Two Bros.full exhaust,K&N air and dyno jet kit.Plugs look nice light brown. Please!!! Any Help Would Be Greatly Appreciated!!!!!! Scott M.
Do they move freely using slight finger pressure? If not then you have grit in the slides. If they do, then you have two possible solutions. 1) The diaphragms are holed or split. 2) The sub filter is clogged and stopping the passage of air as the slides are pushed up. HTH and good luck.
