Check the compression. Low compression with do that. They will run OK at higher RPMs but stall at idle. IIRC, they should have around 100psi, and not lower than 90. They should also be within 10% of each other. Also, some cheap gauges will read low, so try to use a decent one.

• This reply was modified 1 year, 6 months ago by reivertom.
• This reply was modified 1 year, 6 months ago by reivertom.

My money is ultimately with Dave’s solution; but it is ALWAYS good to start with a compression and spark test, pretty much every time, so you don’t go off half-cocked, down some worm hole. You don’t want to waste time or money if the compression is bad. Also, with Big Twins and others, it perfectly possible that spark on one cylinder might be dropping out at low speed. Check compression first, spark second and then go after the carb. When checking the spark, make sure in your case, that the mag plate is in the idle position, because sometimes, wires chafe and will only short out in one place in the throttle travel.