The Husqvarna 55 Rancher chainsaws use a single spark plug. The spark plug gap setting refers to the distance between the electrodes of the spark plug on the end of the plug projecting into the combustion chamber. An improper spark plug gap can cause hard starting, rough running and inefficient burning of the fuel-air charge. Replace the spark plug after a month of operation; but clean and regap the plug as needed to correct performance problems. Adjust the spark plug gap using basic tools.
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.