A chainsaw, when properly adjusted, should rev up smoothly when increasing the engine speed and should not emit excessive smoke. When a chainsaw carburetor is improperly adjusted, or as the chainsaw ages and the carburetor adjustment gets out of adjustment, clouds of smoke can be emitted as it is operated. An improperly adjusted carburetor can also reduce the life of the chainsaw engine. Learn how to adjust a chainsaw carburetor to make your chainsaw run smoothly and efficiently.
Check the fuel level in the fuel tank. The fuel tank should be at least filled to the halfway mark. If there is less fuel, it will make correctly adjusting the carburetor more difficult.
Gain access to the chainsaw carburetor. This can vary with the model and manufacturer of your specific chainsaw. Generally you will need an adjustable wrench and a hex nut driver to remove bolts from the housing of the chainsaw. Remove the housing. The carburetor adjustments will be small screws near the engine.
Start the chainsaw engine and wait for three minutes. This allows time for the engine to warm up, which is needed to correctly adjust the carburetor.
Turn the idle adjustment screw. You'll hear the engine speed up or slow down as you turn the screw. Set your engine idle so that the engine runs at a high speed. This will help prevent the engine from turning off unintentionally.
Turn the screw adjustment for low speed. Turn it one way until the engine begins to run roughly. Turn the screw the other way until the engine begins to sputter. Mentally note the two screw positions and turn the screw so that it is midway between these two points. Pull the chainsaw trigger slightly to check if your low speed adjustment.
Pull the trigger for full throttle speed of the chainsaw. If the engine sounds like its running smoothly with a slightly rough edge, the screw for the full speed adjustment is properly set. If the engine sputters and coughs, adjust the screw and pull the trigger again. Repeat until the full speed of the chainsaw sounds smooth.
Reinstall the chainsaw housing.