I just put in a new jet kit and pulled the plug after the first 2 rides and it is running rich. My friend that is an auto mechanic said that I should go down to the next lower jet size. Is this right or can I just adjust the air/fuel screw? He said that the air/fuel screw will really only help at idle speed and not too much when under power. Just wondering what to do, change jet or air/fuel adjust??? Any help would be great.