How to Identify Bad Spark Plugs on a Polaris ATV

A bad spark plug in your engine can cause loss of power at high speed, misfiring, faulty acceleration and rough starting. To identify a bad spark plug in a Polaris ATV, you must locate and look at one of your plugs. If you have a faulty choke, the plug looks different from a plug in an engine that cools incorrectly.

Difficulty: Easy

Instructions

1. Remove your spark plugs from the engine. You can remove one at a time to check, or you can remove all of them.

2. Look at the spark plug to see its color. The insulator should be light in color and a bit darker on the outside.

3. Check for discoloration to the insulator, which could indicate that your plug wasn't tightened properly, that the engine isn't cooling properly, the timing is to fast or that your plug's heat range is to hot.

4. Feel the spark plug. A spark plug that's wet, black and oily indicates a foul carburetor, or that there is a problem with the piston rings, valve guides or cylinders.

5. Replace faulty spark plugs as an inexpensive way to help correct certain problems with your ATV. Also use spark plug problems to give you an idea of what other issues you ATV may be experiencing.

Tips & Warnings

• Even if your plug still sparks, you must replace a discolored spark plug. It may not actually function properly in the cylinder, or it may spark improperly, causing your engine to misfire or to have trouble starting.