Spark Plugs & Glow Plugs
About Spark Plugs & Glow Plugs
A spark plug ignites the fuel and air in the cylinder, and its thread size, reach and heat range are matched to the engine, so two plugs that look alike are not interchangeable. Owners shop here when a machine is hard to start, misfires, idles roughly, or is due for the plug change in its service schedule.
Start with the plug number in your owner's manual, which is often also stamped on the old plug. In NGK codes such as the D8HA and LMAR9AI-8D in this category, the letters and numbers identify the thread size, heat range and construction. Standard plugs use a nickel or copper-core electrode, and iridium plugs use a fine iridium tip. Heat range matters: a plug that runs too hot or too cold for the engine can overheat or foul, so keep to the range the manual lists. Spark plug caps are listed here too, and glow plugs are the ignition parts for diesel-powered machines.
Brands include DRC, NGK Spark Plugs, Denso, Fire Power and SP1. Pick your machine in the Ride Finder at the top of the page, and see why a part didn't fit for how to double-check. If a new plug does not cure a misfire, look at Ignition Coils and Wiring Harnesses, Cables & Connectors, in the same Electrical & Ignition Components group.
FAQs on spark plugs and glow plugs
How do I find the right spark plug for my ATV or UTV?
Check your owner's manual for the plug number, or read the number stamped on the old plug. You can also pick your machine in the Ride Finder and compare the plug code in the listing. Do not choose by thread size alone, because heat range and reach also have to match.
What does spark plug heat range mean?
Heat range describes how quickly a plug carries heat away from its tip. A hotter plug holds heat and a colder one sheds it faster. The engine maker picks the range for the engine, so stay with it unless the manual or an engine builder advises a change.
Is an iridium spark plug better than a standard one?
An iridium plug has a fine-wire center electrode that is built to hold its shape longer than a standard plug. It suits owners who want less frequent changes. It must still be the plug number approved for your engine, and you should not expect extra power from it.
Do I need to gap a new spark plug?
Check it, even if the plug is sold pre-gapped. Use a wire or feeler gauge and set the gap to the figure in your manual. Bend only the outer ground electrode, and never press on the center electrode, especially on fine-wire iridium plugs.
When should the spark plug cap be replaced?
Replace the cap if it is cracked, corroded or loose, or if the engine misfires when it is wet. A worn cap can leak spark. It is easy to change at the same time as the plug.
