- 1). Empty any old gas still left in the tank. Dump it out into the fuel container if it's been in the tank for more than 72 hours. Fill the chain saw with freshly mixed chain saw gas.
- 2). Unscrew the cylinder and air filter cover. Unhook the air filter from its mount and take the foam pad out. Wash the pad in warm, soapy water. Rinse under cool water after and let it dry out for at least three hours. Never adjust the chain saw with a dirty air filter or bad gas in the tank.
- 3). Start the chain saw's engine and squeeze the trigger lightly to let it warm up at a high idle for several minutes. Locate the carburetor adjusting screws. On some chain saws, they can be accessed on one of the sides of the engine through three small holes. On other chain saws, the cylinder cover, air filter and air filter box may need to be removed to access the adjusting screws.
- 4). Insert the small screwdriver into the idle-speed adjusting screw. Rotate the screw clockwise until the clutch engages and the chain starts spinning. Stop turning and rotate the screw counterclockwise until the chain stops spinning. Find the highest idle speed before the clutch engages.
- 5). Insert the small screwdriver into the low-speed adjusting screw. Rotate the screw slowly clockwise until the engine starts surging at a high-pitched whine. Stop turning and rotate the screw counterclockwise until it starts bubbling at lower noise.
- 6). Find the optimum low speed between the surging and bubbling sounds. Listen for a clean, smooth burning sound while still able to accelerate properly. Reset the idle speed screw as it will likely have changed. Follow the same idle-speed setting method.