The proper adjustment and cleaning of spark plugs can have a significant impact on how an engine runs. It is very easy to overlook these tasks until the engine misfires or stops, but if they are performed every few thousand miles (between 5,000 and 9,500 km, depending on how hard the engine works), both performance and economy should be maintained, and starting problems avoided.

Check the color and condition of the spark plugs after you’ve removed them before cleaning or discarding them. This can provide information about the condition of the rest of the engine. A portable electric spark plug cleaner is available for purchase. Such devices are beneficial. When the electrodes are noticeably thin or short, this could be used. Use a contact file to clean the spark plug electrodes, before resetting the gap, which should be checked by a feeler gauge.

Wipe down the white insulator with a cloth and clean out the threads with a wire brush. Before installing the plugs, smear a little graphite grease on the threads to make future removal easier. Avoid over tightening the plugs. When replacing plugs, only use the recommended type or a direct equivalent. Never assume that the gaps on newly supplied plugs are correct; always double-check them.