How to Adjust the Carburetor on a Small Two-Stroke Engine
The carburetor on a two-stroke engine has a mixture setting for the idle speed and a mixture setting for the high speed. Adjusting the carburetor for this type of engine is part of the process that is known as tuning the engine. Tuning a two-stroke engine will keep it running at peak performance. You can adjust the mixture settings on the carburetor by turning two screws that are located on the carburetor.
Locate the two adjustment screws on the carburetor. One screw is for the idle speed or low speed; the other is for the high speed.
Turn both of the screws counterclockwise to back them out. This will set them in the "open" position.
Turn each screw clockwise two full turns. This will be the starting point for adjusting the carburetor.
Start the engine and let it warm up for a minute or two. Adjust the choke lever to help start the engine, if needed.
Turn the screw for the idle speed clockwise until the motor sounds like it is going to stall, then turn it counterclockwise ¼ to ½ turn.
Hold the throttle for the engine wide open to run the engine at high rpm. Turn the screw for the high speed counterclockwise until the engine begins to run smooth, then turn it ¼ turn clockwise.