I'm trying to troubleshoot the problem I'm having getting this motor to run and idle. It backfires at idle once the choke opens, and won't stay running without squirt from the accelerator pump.
I have the same problem, what I have been doing is check the plugs. With engine cold remove 1 or 2 plugs. With your condition I bet they are black. Rich mixture. Try re-Jetting the carb. Check the main jet. You should try one size smaller.
