It might be a pain in the ***, but if all else fails, put the old carb back on &amp\\; see if that fixes it.&nbsp\\; If it does, that's the problem.

 

I had a 74 Pinto that did the same thing .&nbsp\\; It was a timing issue.

 

Set the idle down to 850-900 if you have a stock cam.

 

Two reasons I can think of to cause it are idle to high and timing to far advanced.

 

Try higher octane gas. Most high compression engines run-on or ping without high octane.

The ignition timing could not be the cause, because you are turning off the ignition when the bike is shut down.

Until you fix it just leave it in gear when you shut it off.

 

Did you hook up the VOES, if not then you would have a vacum leak. Check for a vacum leak.