Changing Spark Plug

Learn How To Check your lawn mowers spark plug & lead

Tools/Parts Required 

  • Spark Plug Spanner
  • Pliers
  • Replacement Spark Plug
  • Spark Plug Boot If Necessary 

Step 1.

To begin with we removed the spark plug from the engine.

Step 2

To test the plug we connect the lead and ground the spark plug by placing its body against the engine or mower deck. The pull-start must then be pulled; whilst doing so observe to see if sparks occur. If no sparks are present it’s likely your spark plug is broken, however, you should check the lead and boot carefully for any imperfections as this can cause the circuit to ground before electricity reaches the spark plug.

Step 3

To test the lead you need to remove the boot and hold the metal end within a few millimetres of the engine’s metal fins, then pull the starter and observe if the lead sends sparks to the engines metal fins; be careful to avoid electric shock, hold the lead with your pliers, keeping your hands on the rubber grip.

If your spark plug lead shows no signs of sparking its likely that your ignition coil, ignition points or CDI (capacitor discharge ignition) are the problem. These are a more challenging repair and will be tackled in future tutorials.

Step 4

If a spark is present then it’s time to test your new spark plug. Once your new spark plug is tested, and you have confirmed it is sparking, then it can be installed into your lawn mower. Hopefully that is the only problem and all should be running well.


  1. hi,can anyone help? carby one victa 2 stroke will not let fuel in, plenty of fuel in the tank,fuel runs to carby & that is where it stops thanks.

    • Hi Barry

      I would remove the brass main jet and ensure that there is no blockages, I would also use a small sewing needle to ensure that the small hole in the carburetor body behind this jet has no blockages.

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