"I have the same motor and it
"I have the same motor and it actually idles quite well. I bought it last year and it ran terribly. I rebuilt and synched the carburetors, adjusted the timing and replaced the plug wires...This made a big difference. The idle mixture screws are extremely sensitive and require some fine adjustment...adjust them slowly and give the engine a chance to stabilize after making small changes. The 2 to 4 cylinder transition at 1800 RPM is still annoying but you learn to open the throttle a little faster to minimize the effect. The transition downward from 4 to 2 cylinders also takes some getting used to. It takes about ten seconds for the motor to smooth out and idle smoothly again...I believe this is due to time it takes to burn up the residual gas that was in the crankcase when the throttle was open on the bottom cylinders. All in all, it's a great motor and it will idle if properly adjusted."