How to check and adjust the spark plug gap on a lawn mower

Checking and adjusting the spark plug gap on your Husqvarna lawn mower is a simple but important maintenance task.

A correct spark plug gap ensures efficient engine ignition and smooth performance.

What is a spark plug gap?

The spark plug gap is a distance between the centre electrode and the ground electrode on a spark plug. This gap allows and electric spark to ignite the fuel-air mixture in the engine.

• Too small? The spark may not ignite the mixture properly.
• Too large? The spark may struggle to jump across the gap, causing hard starts or misfires.

Tools you can use to measure spark plug gap

To measure the spark plug gap on your lawn mower you can use:

• a feeler gauge
• a spark plug gap tool (wire or blade style)
• a coin (as a rough alternative)

Gently slide your tool between the electrodes to measure the gap. Be careful not to damage the centre electrode—it is delicate and critical for performance.

How to check if the spark plug gap is correct

• Too wide? If the tool slides too easily without touching, the gap is too large.
• Too narrow? If the tool does not fit at all, the gap is too small.
• Just right? If the tool fits snuggly with slight resistance, the gap is correct.

How to adjust a spark plug on a lawn mower

If the spark plug needs adjusting:

1. Hold the spark plug with the electrodes facing down.
2. To narrow the gap: Lightly press the ground electrode towards the centre electrode.
3. To widen the gap: Gently bend the ground electrode away from the centre electrode.
4. Re-check the gap using your measuring tool.
   NOTE: Always handle the spark plugs with care. Spark plugs are fragile and can break if bent too far.

What is the correct spark plug gap for my Husqvarna lawn mower?

The correct spark plug gap varies by model. Always refer to the product’s operator’s manual or the spark plug packaging for recommended measurements.

As spark plugs age, the electrodes wear down causing the gap to widen. This can lead to hard starts and inefficient combustion.

Regularly checking and adjusting the gap can extend the life of your walk-behind lawn mower and keep it running smoothly.

Final tips for better lawn mower performance

• Check the spark plug gap every season or every 25 hour of use.
• Replace spark plugs that are worn, corroded or cracked.
• Always use the recommended spark plug type and gap setting for your specific lawn mower.

By keeping the spark plug gap in check, you ensure your Husqvarna lawn mower starts easily, runs smoothly and performs at its best.