How to set the spark plug gap on your lawn mower

Setting the correct spark plug gap on your lawn mower is crucial, as it may cause damage to the engine if the gap is incorrect.

The best way to set the correct spark plug gap is by using the feeler gauge.

Measure the gap by passing the feeler gauge through the electrodes

Place the appropriate blade or wire on your feeler gauge between the electrode tips of the plug.

Determine if the gap needs adjusting

If the feeler gauge passes through the gap without touching the electrodes at the appropriate measurement, the gap is too wide. If you cannot fit the tools between the electrodes, the gap is too small and needs to be widened. If it fits closely to the specific measurement, you can install the spark plug.

Use the feeler gauge to adjust the bottom spark plug

When you hold the spark plug with the electrodes facing the floor, bend the bottom electrode very gently in towards the other electrode if you want to narrow the gap, or out if you want to increase the gap slightly.

• Never bend the electrode in/out too much, as the spark plugs are very delicate and any fracturing can cause misfires.
• If you are having trouble using the feeler gauge to adjust the gap, consider bending it using a flat surface like a table, as this will apply very gentle pressure on the electrode in order to adjust it.