You will be able to clean a chainsaw carburetor more efficiently if you understand that its two basic functions are to deliver air and fuel to a combustion chamber in the engine. This should help you understand that in cleaning the carburetor, you may need to clean the channels for both air and fuel. This can be done in 5 simple steps.
Step 1 - Clean the Air Filter
When cleaning a carburetor of a chainsaw that doesn't start, check the air filter. If the filter is dirty or clogged, it will be apparent when you examine it. A clogged or dirty filter will prevent needed air from being drawn into the carburetor's combustion chamber. A dirty or clogged filter, if it's metal, can sometimes be cleaned by swishing it in a liquid cleaning agent. If the filter is made of paper or other material likely to disintegrate in liquids, you will probably need to replace it.
Step 2 - Clean Carburetor Intake Components
Once your air filter has been replaced or cleaned and all the saw's parts are in place, try starting it again. If it still won't start, you'll then need to check the air intake surfaces for a gummy residue. This residue is typically gold or brown in color and should be easily visible on the surface of air intake components. If you spot this kind of residue you should be able to clean it easily by spraying the gummed surface with a spray cleaner.
Step 3 - Clean Carburetor Needle Valves
If you still have problems starting the chainsaw, check the carburetor's needle valves that may also be gummed up by fuel deposits. Any of these deposits left in the carburetor can usually be dissolved by fuel added to the fuel in the saw's gas tank.
Step 4 - Operate the Pull Cord
Give your pull cord several strong pulls, alternating with several pauses to allow the additive to dissolve gummy deposits. Sometimes this cleaning requires a flow of fuel with the cleaning agent in it over these gummed up surfaces. Even though the saw may not be running yet, just pulling the cord, when combined with a few rest intervals, can move the cleaning agent through the carburetor valves enough to clean off any residue left on their surfaces.
Step 5 - Use Fresh Fuel
At times the problem may be caused by old fuel or fuel into which moisture has condensed and contaminated the old fuel. If this is the case, empty the old gasoline from the tank and refill it with fresh gas.
If all this cleaning fails to correct the starting problem, you may have no other choice but to take the saw to a small engine shop where mechanics have been trained to repair chainsaws.