1. Remove the air filter cover and remove the air filter.
2. Locate the main jet screw on the carburetor. The main jet screw is usually located on the side of the carburetor, underneath the air filter housing.
3. Turn the main jet screw clockwise to make the mixture leaner (less fuel) and counterclockwise to make the mixture richer (more fuel).
4. Start the engine and let it warm up to operating temperature.
5. Ride the motorcycle at various speeds and observe the engine performance. If the engine is running too lean, it will hesitate or sputter when you accelerate. If the engine is running too rich, it will run rough and may produce black smoke from the exhaust.
6. Adjust the main jet screw until the engine runs smoothly at all speeds.
7. Replace the air filter and air filter cover.
Adjusting The Pilot Jet
1. Remove the fuel tank.
2. Locate the pilot jet screw on the carburetor. The pilot jet screw is usually located on the bottom of the carburetor, near the throttle valve.
3. Turn the pilot jet screw clockwise to make the mixture leaner (less fuel) and counterclockwise to make the mixture richer (more fuel).
4. Start the engine and let it warm up to operating temperature.
5. Turn the idle speed screw until the engine idles at a low, smooth speed.
6. Adjust the pilot jet screw until the engine idles smoothly without any hesitation or surging.
7. Replace the fuel tank.
