How To Inspect, Replace, and Install ATV & UTV Spark Plugs

Generally speaking you will want to replace the spark plug(s) after each 100 hours of use. This assumes of course that your engine is running normally and you are not experiencing problems like a "rough engine" or an engine that fails to catch while the ignition is turning over. If these occur it's time to pull the plug and determine if it is the problem or some other component is the cause.

Actually pulling the plug, inspecting and replacing it only takes 5 to 10 minutes. However, unlike a car you can't pull a handle and pop the hood to get to the spark plug. On an ATV you have to remove plastic (exterior panels) to expose the plug and depending on your brand that could be a lot of plastic. Pulling off parts is the real time consumer for this task.

Because it takes a bit of work to "open up" your ATV it's a good idea to check a couple of items while they are easily accessible. Make certain that the bolts on the battery cables are firmly attached to the battery posts. A common "won't start" problem is often the result of hard riding loosening the bolts from the battery terminals.

Your exhaust system is another component that is accessible in most models when you have sufficient exterior panels removed to get to the spark plug. Check the bolts holding the pipe to the engine to ensure a secure fit.

The steps we provide below are general in nature and are not meant to replace the instructions found in your OEM owner's manual. Obviously different brands have different engine mounting configurations meaning the location of the spark plug and how easy it is to access will vary. When in doubt, follow the OEM instructions. Our tips are intended to show you that this repair can be done as a DIY project saving you professional labor costs and a more enjoyable ATV experience.

• Shop rags
• Screwdriver (to remove exterior panels)
• OEM Spark Plug Pulling Tool or a socket, driver and extensions
• Wire Gauge
• Socket wrench set
• OEM Manual
• "Fine" Sandpaper
• WD 40

1. Refer to your OEM manual to determine which piece(s) of plastic you need to remove to gain access to the spark plug. If you don't have the manual check the manufacturer's site online and see if they have one for download.
2. Remove the plastic.
3. If you are unsure where the spark plug is just follow the spark plug wire (blue or red) to the boot. The plug is under the boot.
4. Spray a little WD 40 around the boot and the surrounding area and then wipe clean. The last thing you need is debris falling into the engine once you have pulled the plug.
5. Grab the spark plug wire boot and pull in the same direction that the plug is pointing. This may require a bit of effort so look to see where your hand is going to go when the boot snaps free to avoid a scraped knuckle.
6. With the boot off slide the OEM plug puller tool over the plug and turn counterclockwise to unscrew. If you don't have the manufacturer's tool use a socket, driver and extension and do the same thing. If the plug is difficult to move, spray a little WD 40 around the base and wait a minute.

1. Even if you plan to replace the plug with a new one, inspect it and see if it's wet or smells of raw fuel. If so you may have a break in the engine seal. If you have pulled it just to clean it you can use WD 40 or fine grade sandpaper to remove carbon buildup. Use the gap gauge to set the gap and then reinstall.
2. If the starter works but the engine won't catch it may be the plug or the spark plug wire. Clean and set the gap of the plug and then connect it to the spark plug wire. Hit the ignition and see if the plug gives off a good spark. If it doesn't, try the same test with a new plug. If there is still no spark the problem is most likely a faulty spark plug wire.

1. Basically you are going to do the same steps as "remove" only in reverse.
2. Make certain the new plug is set at the correct gap.
3. Insert the plug and tighten by hand if you can. Use the plug puller tool or socket for the final quarter to half turn. Do not over tighten the plug. Most ATV engine blocks are made of soft metals and you can damage them if you apply too much pressure to the plug.
4. Check the connections inside the spark plug wire boot for dirt or carbon and clean if needed. Place the boot over the plug and push down until you hear it snap into position.
5. Before you go to the effort of reinstalling the plastic, press the starter and make certain your plug is firing.
6. Reinstall the plastic.

Replacing the spark plug is a simple DIY task that almost anyone can accomplish in a minimal amount of time.

- End of Procedure -

Return to all Repair & Install Guides