Carburettors are essential to proper fuel to air mixture on many of the small engines found on Stihl lawn and garden equipment. They deliver the gasoline and mix the fuel with the air to ensure complete, efficient combustion. Adjusting a carburettor on a Stihl Chain Saw is crucial to proper engine response and clean, consistent cuts. Adjusting the carburettor is not exceedingly difficult and, with a bit of practice, can be mastered by almost anyone.
Use the screwdriver to remove the right-hand motor shroud from the chainsaw. The carburettor is the small, metal, rectangular apparatus underneath the shroud.
Use the screwdriver to pry the thin metal wire off the bottom of the carburettor, also known as the "float bowl." Pull the float bowl out of the engine compartment, and inspect the gas level. The bowl should be about halfway full, and the you must adjust the float if it is more or less full.
Adjust the float (the round metal apparatus that fits inside the float bowl) by bending the small metal tab at the rear of the float pivot. Once the float is adjusted to your liking (based on your inspection of the float bowl), reinstall the float bowl and metal mounting wire.
Locate the jet screw on the top of the carburettor. This controls the amount of air allowed into the carburettor and should be set about ten turns out. Use the screwdriver to adjust the screw accordingly.
Start the chain saw, and listen to its idle. Experiment by adjusting the set screw with the saw running. Once it idles smoothly, replace the engine shroud.
When working with any flammable material, such as gasoline, make sure you are not near any sparks or sources of ignition.