Grass Trimmer & Brushcutter

How to check a spark plug gap on a petrol product

If your Husqvarna product is hard to start, running unevenly, or losing power, the spark plug gap may need adjustment.

This guide shows you how to check and fix it quickly.

Quick answer

  • Use a feeler gauge to measure the gap between the electrodes
  • The tool should fit snugly—not too loose, not too tight
  • Adjust slightly if needed

Safety first

  • Turn off the product and let it cool
  • Disconnect the spark plug before inspection
  • Work in a clean, well-lit area
  • Handle the spark plug carefully

What is a spark plug gap?

Learn more about the spark plug gap

The spark plug gap is the space between the two electrodes where the spark is created.

  • If the gap is too small, the spark may be weak
  • If the gap is too large, the spark may not form properly

If the gap is incorrect, the engine may not start or run properly.

When should you check the spark plug gap?

Learn when to check the spark plug gap

Check it if your petrol-powered product:

  • Is hard to start
  • Runs unevenly
  • Loses power
  • Uses more fuel than usual

Watch how to check and adjust the spark plug gap

Watch this quick video to see how to measure and adjust the spark plug gap:

How to check the spark plug gap

Learn how to check the spark plug gap

Remove the spark plug

  • Use a spark plug wrench to remove it from the engine

Measure the gap

  • Use a feeler gauge or wire gauge
  • Slide it between the electrodes

Result:

  • Fits snugly—gap is correct
  • Too tight—gap is too small
  • Too loose—gap is too wide

Adjust the gap if needed

  • To make the gap smaller: gently bend the outer electrode inwards
  • To make the gap larger: gently bend it outwards

Make small adjustments only. Spark plugs are delicate.

Reinstall the spark plug

  • Screw it back in securely
  • Reconnect the spark plug

What is the correct spark plug gap?

The correct gap depends on your model.

  • Check your operator’s manual for exact specifications
  • Using the wrong gap can affect starting and performance

Common mistakes to avoid

  • Skipping the measurement step
  • Bending the electrode too much
  • Using the wrong tool
  • Damaging the centre electrode

Still having issues?

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