How to Replace a Spark Plug in a Dirt Bike

Replacing the spark plug in a dirt bike is a simple task that anybody can perform. With the proper tools, replacing the spark plug takes approximately five to ten minutes. There are multiple reasons to replace the spark plug in a dirt bike. For instance, the old spark plug may foul, meaning part of the spark plug burns up. In this case, the dirt bike will not run. A spark plug can be replaced anywhere as long as the rider has the required tools.

Figure 1 - Required Tools and Equipment
Figure 1 - Required Tools and Equipment

Required Tools and Parts (Reference Fig 1)

  1. New Spark Plug

  2. Spark Plug Socket

  3. Socket Attachment

  4. Spark Plug Gap Setter

The Steps to Replace a Dirt Bike Spark Plug:

  1. Obtain the Required Tools and Parts

  2. Locate the Spark Plug

  3. Remove the Used Spark Plug

  4. Set the Spark Plug Gap

  5. Insert the New Spark Plug

Figure 2 - Standard 5/8 Inch Spark Plug Socket
Figure 2 - Standard 5/8 Inch Spark Plug Socket

1. Obtain the Required Tools and Parts

The first step is to obtain the necessary tools and parts to replace the spark plug. The correct spark plug model to purchase will be defined in the owner’s manual for the dirt bike. A spark plug for a dirt bike can be purchased at any store that sells dirt bike parts.

The tools needed to replace the spark plug are made specifically for spark plugs. For instance, a spark plug socket will only work on a spark plug and nothing else. The socket attachment is a tool that allows the user to apply a torque on the socket. For newer sockets, this attachment is a ratchet. For older sockets, such as the one illustrated in Figure 2, the attachment is a shaft. This socket has two holes at the top allowing the shaft to fit into the holes.

A spark plug gap setter is also required to set the correct spark plug gap. This setter, along with the previously mentioned tools, can be purchased on-line or at a parts store such as AutoZone.

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Figure 3 - A Standard Dirt BikeFigure 4 - Zoomed View of Red AreaFigure 5 - Zoomed View of Blue Area
Figure 3 - A Standard Dirt Bike
Figure 3 - A Standard Dirt Bike
Figure 4 - Zoomed View of Red Area
Figure 4 - Zoomed View of Red Area
Figure 5 - Zoomed View of Blue Area
Figure 5 - Zoomed View of Blue Area

2. Locate the Spark Plug

After obtaining the required tools and equipment, the next step is to locate the spark plug. The pictures illustrated are designed to assist in locating the spark plug. The spark plug will be located within the area outlined by the red rectangle shown in Figure 3. This is where the engine is located. The spark plug attaches to the top of the engine. A blown up view of the red rectangular area is shown in Figure 4. Finally, Figure 5 depicts the area of interest. Seen in Figure 5 is the spark plug wire attached to the top of the spark plug.


Figure 6 - Spark Plug without Wire Attached
Figure 6 - Spark Plug without Wire Attached
Figure 7 - Socket Attached to Spark Plug
Figure 7 - Socket Attached to Spark Plug
Figure 8 - Used Spark Plug
Figure 8 - Used Spark Plug

How to identify a fouled spark plug

3. Remove the Used Spark Plug

CAUTION!

The spark plug and surrounding parts will be extremely hot if the bike was recently running. To avoid being burned, allow the bike to cool for five minutes before removing the spark plug.

Now that the spark plug is located, the next step is to remove the spark plug. Begin by removing the spark plug wire that is attached to the spark plug. This is done by pulling the wire upwards. The spark plug without the wire attached is illustrated in Figure 6.

Fit the spark plug socket over top of the spark plug and slide the shaft through the two holes in the top of the socket (or for newer sockets, fit the ratchet onto the socket). Apply a torque on the shaft or ratchet in the counterclockwise direction to loosen the spark plug from the engine. This configuration is illustrated in Figure 7. Depending on the make and model of the dirt bike, it may take multiple efforts to loosen the plug since this area is very tight.

After the spark plug is loose, the spark plug socket and attachment are no longer needed. The spark plug can be loosened by hand. Continue loosening the spark plug in a counterclockwise direction until it is released from the engine. A removed spark plug looks similar to the spark plug depicted in Figure 8. Notice the black area on the left side of the spark plug. This is a sign that the plug is worn and needs replaced. Discard the used spark plug.

Occasionally, a used spark plug can be reused. This is not recommended unless the rider does not have a new spark plug at their disposal. In this instance, use a wire brush and perform back-and-forth brushing motions on the black area of the spark plug. Continue this for approximately two or three minutes. The used spark plug can then be inserted into the engine.

Figure 9 - Spark Plug Gap
Figure 9 - Spark Plug Gap
Figure 10 - Spark Plug on Gap Setter
Figure 10 - Spark Plug on Gap Setter

4. Set the Spark Plug Gap

Before inserting the new spark plug, set the spark plug gap. The spark plug gap is displayed in Figure 9 (InstallUniversity). This length is specified in the owner’s manual for the dirt bike. For example, spark plug gaps typically range from 0.02 inches to 0.10 inches.

To set the gap, place the spark plug onto the spark plug gap setter in a manner similar to Figure 10. Slide the spark plug along the spark plug gap setter until the desired length is reached. The numerical values are displayed on the gap setter.

How to set the gap on your spark plug

Figure 11 - Spark Plug in Engine
Figure 11 - Spark Plug in Engine
Figure 12 - Final Configuration
Figure 12 - Final Configuration

5. Insert the New Spark Plug

Now that the spark plug gap is set, the final step is to insert the new spark plug into the engine. Begin by inserting the spark plug into the engine in the manner illustrated in Figure 11.

Hand-tighten the spark plug by twisting it in a clockwise direction. Continue this twisting until the spark plug feels tight. As mentioned previously, fit the spark plug socket over top of the spark plug and slide the shaft through the two holes in the top of the socket (or fit the ratchet onto the socket). This time, apply a torque on the shaft in the clockwise direction to tighten the spark plug into the engine. Do not over tighten the spark plug. It should not take more than a quarter of a rotation to secure the spark plug into the engine. Remove the spark plug socket and securely fasten the spark plug wire over the spark plug. The final configuration is illustrated in Figure 12.

Review

There are five steps to follow when replacing the spark plug in a dirt bike:

  1. Obtain the Required Tools and Parts
  2. Locate the Spark Plug
  3. Remove the Used Spark Plug
  4. Set the Spark Plug Gap
  5. Insert the New Spark Plug

First, obtain the required tools and equipment. These tools and equipment consist of a new spark plug, a spark plug socket, a socket attachment, and a gap setter. Next, locate the spark plug on the dirt bike. After that, remove the used spark plug using the spark plug socket and attachment. Then, use the gap setter to set the gap on the new spark plug. Finally, insert the new spark plug into the engine.

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Comments 1 comment

john hayls profile image

john hayls 4 years ago

I get new thing after reading this blog. This is really helpful information for those people who have bike. Thanks for the shearing the information. Good work.

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