In this video, we show you how to change a spark plug on a Stihl TS420 disc cutter.

Health & Safety Warning - Please ensure that you have safely prepared the machine and workspace. If you are unsure about any aspect of the task please seek professional advice.

Transcript

Today we're going to change the spark plug on a Stihl TS420 Disc Cutter.

First of all, using the torx spanner unscrew the screw located at the top of the machine next to the starting button to remove the cover from the machine.Then pull up on the spark plug cap to remove from remove from the spark plug.

Now use the 19mm Hex Socket Spanner to unscrew the spark plug. Inspect the old spark plug and see of there's any damage to the seal ring. There's a clear difference between the new and old spark plugs. The old one has a compressed squash ring and looks biscuit coloured.

Hand screw the new spark plug in, being careful not to damage the thread. You can then return to tighten it with the 19mm Hex Socket Spanner. Locate the cap back on top of the spark plug, making sure it's secure. Then place the casing back over it, and screw it back on using the torx spanner.

That's how you change the Spark Plug on a Stihl TS420. All the parts & tools needed for this task are listed in the description below.

Parts

Parts and tools included in the TS420 disc cutter how-to video.

• Genuine NGK BPMR7A Spark Plug - BPMR7A
• Genuine Spark Plug Cap - 1128 405 1000
• Non Genuine Spark Plug Cap 410 601
• Plug Cover/Cap & Screw - 4238 080 2200
• Non Genuine Plug Cover/Cap & Screw - 410 631
• Genuine Torx Wrench/Plug Spanner - 4224 890 3400
• Non Genuine Torx Wrench/Plug Spanner - 410 250

Hanging the spark plug on a Stihl TS420 disc cutter is a straightforward process, but it's essential to follow the steps correctly to ensure the safety and longevity of the equipment. Here's a step-by-step guide:

How to Change a Spark Plug on a Stihl TS420 Disc Cutter

1. Safety First:

- a. Always ensure the machine is turned off and has cooled down before starting any maintenance.

- b. Wear protective gloves and safety glasses to protect your hands and eyes.

2. Gather Necessary Tools:

- a. A spark plug wrench or socket wrench.

- b. A new spark plug compatible with the Stihl TS420.

- c. A clean cloth or rag.

3. Access the Spark Plug:

- a. Locate the spark plug cover on the machine. It's typically on the side of the engine.

- b. Remove the spark plug cover by unscrewing or unclipping it, depending on the model.

4. Remove the Old Spark Plug:

- a. Disconnect the spark plug boot (the rubber cap connected to the spark plug).

- b. Using the spark plug wrench or socket wrench, turn the spark plug counterclockwise to loosen and remove it.

- c. Once loosened, you can use your hand to unscrew and remove the spark plug.

5. Prepare the New Spark Plug:

- a. Check the gap of the new spark plug using a spark plug gap tool. The gap should match the specifications in the Stihl TS420 user manual.

- b. If necessary, adjust the gap by bending the ground electrode (the curved metal piece) until the gap is correct.

6. Install the New Spark Plug:

- a. Hand-tighten the new spark plug into the spark plug hole. Ensure you don't cross-thread or over-tighten, as this can damage the engine.

- b. Once hand-tightened, use the spark plug wrench or socket wrench to tighten the spark plug an additional 1/4 to 1/2 turn.

7. Reconnect and Test:

- a. Reattach the spark plug boot to the new spark plug.

- b. Replace the spark plug cover and secure it in place.

- c. Start the Stihl TS420 disc cutter to ensure it runs smoothly. If there are any issues, double-check your work or consult the user manual.

8. Dispose of the Old Spark Plug:

- a. Old spark plugs can be recycled at local automotive or hardware stores. Check with your local recycling center for specific disposal instructions.

Tips:

- Always refer to the Stihl TS420 user manual for specific details and recommendations.

- Regularly checking and changing the spark plug can improve the performance and lifespan of your disc cutter.

- If the disc cutter doesn't start after replacing the spark plug, ensure the spark plug boot is securely connected and the spark plug is tightened correctly.

By following these steps, you can successfully change the spark plug on your Stihl TS420 disc cutter and ensure it operates at peak performance.