How to Adjust a 2-Cycle Engine Carburetor

Place the engine flat on a work bench. Remove the air filter cover located on the top of the carburetor. Remove the air filter and inspect it, clean or replace.

Remove the spark arrestor from the exhaust port. This is located on the muffler and is held in place by two small screws. Clean the screen by spraying carburetor cleaner on the screen until you can see through all the screen holes. Reinstall the spark arrestor screen.

Start the engine. On the side of the carburetor are three small screws. There marked either on the housing or directly on the side of the carburetor. Adjust the screw marked "L" -- this is the low speed. Turn the screw "L" screw clockwise until it hits the stop. Back off screw in 1/4 turn increments until engine runs smoothly in the idle position.

Advance the throttle to the full throttle position. Adjust the screw marked "H" this is the high speed adjustment, it will be directly beside the "L" screw. Turn the "H" screw counterclockwise until it hits the stop. Back off the screw in 1/4 turn increments, adjusting no more then 3/4 turn, until the engine is running smoothly.

Adjust low idle speed. It will be marked with a "T" or "LA". This is the low idle adjustment. It's located directly under the "L" and "H" screws. If the chain on the blade is turning in the idle position, turn the "T" or "LA" screw counterclockwise slowly until the chain stops turning.

Test the chainsaw from idle to full throttle to ensure that you followed the proper procedure.