Eight steps to cleaning a carburetor
Step 1: Remove the spark plug cap so the engine doesn’t fire during maintenance. Then turn the fuel valve to the off position.
Step 2: Some manufacturers incorporate carburetor drain screws in their engine designs. If this is the case with your engine, simply drain the carburetor bowl by removing the drain screw, which is positioned on the outside of the unit. Once gas is drained, take off the bowl by removing the screw that attaches the bowl to the bottom of the carburetor.
After the carburetor bowl is drained into a container, evaluate the fuel condition. Note whether you see rust, dirt, or corrosion. Generally, if your engine has fallen victim to old gasoline, varnish from stagnant fuel will stick to the bottom of the carburetor bowl.
Step 3: If the carburetor bowl has varnish residue in it, spray the inside with carburetor cleaner and wipe it clean. If the material within the carburetor bowl is still in a liquid state, simply wipe it dry.
Step 4: The main jet’s passage is where fuel flows through the carburetor into the combustion chambers. To inspect the passage, remove the jet with a flathead screwdriver. Be sure you have some sort of pan to catch it.
Step 5: To service the jet and open the passage, spray carburetor cleaner on it and clear out any particles or gummed fuel by passing a wire brush bristle through it. Be careful not to make the passage any larger than its original size.
Step 6: Remove all material that could come loose and clog up the jet again by spraying the rest of the carburetor components with carburetor cleaner, making sure to catch overspray from the cleaner with a rag.
Step 7: The idle jet, which might need service, is at the top of the carburetor. Some idle jets will unscrew on top. Others are pressed in or might be plastic with O-rings to seal them. To clean the idle jet, pass a wire-brush bristle through it to be sure the opening is completely clear.
Step 8: Reassemble by placing the main jet back into the carburetor stem with a screwdriver. Make sure it is snug but don’t overtighten. Check to see the gasket (either flat or O-ring) that seals the carburetor bowl to the carburetor body is in position, not torn or warped. Tighten the screw and washer that holds the carburetor bowl to the carburetor body. Do not overtighten and make sure there is no fuel around the carb bowl.