Harley Spark Plugs, Wires & Plug Caps

For such simple components, your Harley needs to have quality spark plugs and spark plug wires to run. Harley spark plugs will generally last quite a while in a well-running bike, but they do still need to be replaced about every 30,000 miles. A lean or rich running engine may require you to change them sooner. Fouled plugs or burned plugs need to be replaced immediately for the engine to run as it should. Be sure to chase down the cause of bad plugs first, though as a bad plug can be a sign of other problems.

When replacing your Harley’s spark plugs, you can choose an OEM replacement to keep things stock or you can choose a performance plug. Performance plugs are able to produce a hotter spark. This combusts more fuel to produce more power and even better fuel economy. Many performance plugs will often last longer as well. Iridium Harley spark plugs require less voltage to produce a superior spark. They can also handle much hotter temperatures, making them a great choice for high performance engines.

Spark plug wires and caps wear out over time and need to be replaced. A loose cap can even cause a misfire and possibly damage the engine. Performance spark plug wires are designed to transfer current more efficiently and yet are still able to stay cooler. Running cooler also aids in the wire lasting longer. Aftermarket wiring harnesses are available to not only replace OEM harnesses, but they can also aid in performance.