How to Adjust a Western Auto Chainsaw Carburetor

Unhook the fuel container cap and drain out any leftover, unused fuel that's older than one week. Fill the fuel tank with freshly mixed Western Auto chainsaw fuel. Undo the cylinder cover and brush out the area around the cylinder, the air filter and near the carburetor.

Start the Western Auto chainsaw's engine and give it at least 10 minutes to reach operating temperatures. Locate the three carburetor adjusting screws on the sidewalls of the carburetor, usually accessed via the clutch side of the engine.

Set the small screwdriver into the screw set for the idle speed. Turn the screw in clockwise until the engine accelerates and the chain starts spinning. Stop turning the screw and move it counterclockwise until the chain stops again. Find the highest allowable rpm before the chain starts spinning.

Set the small screwdriver into the screw set for the low speed. Turn the screw in clockwise until the engine accelerates again and starts making a whining noise. Stop turning the screw and move it counterclockwise until the engine slows down and produces a bubbling noise.

Adjust the low speed screw slowly between these two high and low points (don't go past these settings or you may damage the engine). Locate the optimum low speed, which will give the best, smoothest acceleration and power. This will also make the cleanest, smoothest engine sounds. Readjust the idle speed screw once the low speed is attained.