These SU HS6 carbs were rebuilt 15 years ago with new shafts with delrin bushings that shouldn't wear out.There hasn't too much use for this is a summer car. They have stock KD needles and I have replaced the rear jet because it was leaking fuel. I did not replace the front jet and this is the carb that has problems adjusting the mixture. Brought the mixture to it's starting point at 12 flats out. When I lift the suction piston there is no difference in idle or rpm.
I could replace the front jet but only reason would be because it might be worn but that doesn't make sense to me. The carbs are clean inside & out.
Scratchin' me head about this problem.