Remove the four screws from the top of the engine cover using a Phillips screwdriver. Lift the engine cover off.
Grasp the boot of the spark plug wire and pull the spark plug wire off the spark plug. Remove the spark plug, using the chainsaw multi-tool or a ratchet and plug socket.
Gently tap the spark plug electrode on a clean, hard surface to slightly collapse the gap. Insert the gap tool into the gap between the electrodes and rotate the tool until the gap reads 0.02 inches.
Install the spark plug and tighten it securely, using the chainsaw multi-tool or a ratchet and plug socket. Snap the spark plug wire on the spark plug.
Install the engine cover and tighten the screws, using a Phillips screwdriver.