I just got done putting in a carb kit and uping my jet sizes fron a 122 to a 125 and 38. I set the pilot screw 2 1/2 -2 3/4 out and it would run good but on hard revs it would puff black smoke out do you think this is carb cleaner burning off ? I used a spark plug to tell if it was running rich or lean and think I have it set good but I am still wondering what up any help?
If it's putting out black smoke, it's running rich. That won't have anything to do with the pilot screw. The pilot screw just adjusts the air/fuel mixture for the idle circuit.
The pilot jet, and pilot screw control fuel delivery from idle to approximately 1/8 throttle. The main jet primarily controls fuel flow between 3/4 and WOT (wide open throttle). The needle and needle jet are the components that regulate fuel flow between 1/8 and 3/4 throttle.
If it idles good and runs good up to about 1/8 throttle, I would just go down a size on the main jet and see what that does.
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