A Craftsman chain saw comes with an adjustable idle speed. By regulating the flow of gas in the carburetor, you can adjust the idling speed of your saw. This screw will open and close a jet inside the fuel mixing chamber on the carburetor. Over-adjusting the carburetor can damage the carburetor and piston. It will also cause the chain to spin during idling, which can be dangerous for the operator.
Open the gas tank and fill the Craftsman with freshly mixed chain saw fuel. Adjusting when the tank is empty can damage the carburetor. Unscrew the top air filter cover with the screwdriver.
Pull the air filter from the box. Wash the filter in warm, soapy water. Rinse with cool water. Let it dry for several hours before reusing it. Do not adjust the carburetor with a dirty air filter.
Start the Craftsman’s engine and let the chain saw idle for a few minutes to warm the engine. Locate the three letters on the starter side of the chainsaw, which read “H,” “L” and “T.” Insert the small screwdriver into the hole marked “T” for the idle speed.
Rotate the “T” screw clockwise to increase the speed of the idle. Rotate the screw clockwise until the chain begins moving on its own. Turn the screw counterclockwise slowly using 1/8-increments until the chain stops spinning. Locate the highest idle speed before the chain starts spinning on its own. This will be your optimum idle speed.