My '01 heritage (carbureted), vance long shots, S&S Super "E", idles approx 1000 RPM. Suddenly it will drop to 400-500 RPM for no reason and wont recover until it dies. Does this warm or cold. No mods to the carb, or engine. Did the same thing with the original Keihn carb. Frustrating at a stop light. Any thoughts?

BTW, new S&S recently installed, new gaskets, no intake leaks. Has done this for a long time (sparadically) but now seems to be getting worse. I was hoping the old original carb was the problem but it seemed to follow to the S&S so wondering VOES bad, or the intake mounted MAP sensor? I'm stumped.

 

check your ignition timing. Also, do you think it's getting too much fuel at idle?

 

It could be to do with the VOES
it is causing the starting timing curve to be selected
this curve is less advanced at idle
so the idle speed drops off suddenly(like flicking a switch, which, in fact, is exactly what would be happening)
check for a leak
check the switch itself
make sure you really are idling at 1000
the switch is adjustable(though factory set-up is quite reliable)
you do not necessarily need a new one(but you might)