I will put this out there.....I tried several attempts to make the 30mm mikuni(Chinese) work. I replaced the jets 115/30. The engine will idle very rough. Any acceleration is just awful....stumbling. Within 2 minutes the plug is loaded with black soot. Checked for air leaks, no leaks. Needle valve adjusted to second notch from the top. Floats adjusted. I have had the carb off a dozen times. I reinstalled the stock carb and it does what it does...at a low load throttle position it stumbles. Full throttle fine. Idles fine. Acceleration fine. Did I buy a bad Carburator? WM suggested the O ring on the manifold, that was in good shape. Help
