Lawn mower plugs may have a shorter thread length than auto plugs. The threads on many automobile plugs are 1/2 inch or 3/4 inch long. Many lawn mower engines use a plug with threads only 3/8 inch long. ... Most mower plugs use a metal gasket washer as a cylinder seal, as do many auto plugs.
To safely clean a spark plug, you should use a wire brush or spray-on plug cleaner specifically designed for this ignition part. You can also use a sturdy knife to scrape off tough deposits. Note: NEVER clean a spark plug with a shot blaster or abrasives.
Removing spark plug boot wires can be difficult without tearing the rubber material. The CRAFTSMAN® Spark Plug Boot Removal Pliers feature specially formed, rubber coated grips that help grab plug wires and protect the rubber boot. The dipped handles provide a comfortable and secure grip.
Using WD-40 to repel water from spark plugs, distributors, alternators, and batteries is a good way to prevent corrosion and keep moisture away. You can also use it to ease the removal of spark plugs, especially if there is any rust or corrosion.
However, you can not spray the carburetor when the engine is off since it cannot do the cleaning without being propelled. All you need to do is to start the engine and spray directly at the center of the carburetor while it is running. Any deposits clogging in the carburetor will easily be removed.