ASK THE MXPERTS: TURNING THE PILOT JET IN OR OUT

The airscrew is the small brass screw just above the fuel line. It can be adjusted with a flat-bladed screwdriver.

TURNING THE PILOT JET IN OR OUT
Dear MXperts,
I know how to adjust the air screw on my YZ250, but to make my bike run better, I have to turn my air screw out three turns. What’s the dealio?

     A two-stroke’s air screw meters the airflow to the pilot circuit of the carburetor, which is controlled by the pilot jet. The typical air screw is set between one and two turns out. Turning the air screw in lessens the amount of air, which richens the mixture, while turning it out increases airflow and leans the mixture. If you have to turn your air screw out more than two turns, you need to change to the next leanest pilot jet (and vice versa). Keep this in mind: an air screw should never be turned all the way in or more than 2-1/2 turns out.