- 1). Spray your motorcycle carburetor with carburetor cleaner to remove any buildup of oil deposits or dust that could hinder the smooth idling of your engine. Use a clean cloth to wipe away any remaining cleaner from the carburetor.
- 2). Start up your motorcycle engine and allow it to idle until the engine is warm. Locate the carburetor mixture screw on the side of the carburetor barrel. It should be running at a 90-degree angle from the carburetor barrel about 2/3 of the way down from the top of the barrel.
- 3). Detach the vacuum hose from the carburetor and attach an RPM gauge to the vacuum port on the carburetor. Your RPM gauge needs to be able to read at least 1400 RPMs.
- 4). Turn the mixture screw with a screwdriver clockwise until you here the engine running at high idle. High idle on a motorcycle engine will be about 1400 RPMs.
- 5). Turn the mixture screw counterclockwise until you hear the idle running at just above the point where it would start to cut out. Normal RPM speed should be between 1000 and1100 RPMs.
- 6). Verify that the engine is running smoothly by removing the RPM gauge and reattaching the vacuum hose to the carburetor. If the carburetor is cutting out at idle, turn the idle screw up to where the carburetor is running on the higher end of the 1000- to1100-RPM scale.