Spark Plug Socket Notes

We endeavor to provide spark plug sockets that will work on your vehicle, but in some applications the CruzTOOLS-supplied socket(s) won't fit. As noted below, there are three principal hex sizes in use; only two of which we provide. In addition, many newer vehicles require a special thin-wall spark plug socket to fit into the head, and at a specific length in order to clear the tank and/or frame. In these cases, you may need to acquire the OEM spark plug tool for your specific make and model.

This may all be somewhat moot, however. With the proliferation of fuel injection and electronic ignition, spark plugs seldom foul or fail, thus limiting removal to regular service intervals.

For Harley-Davidsons

Most kits for Harley-Davidsons include both 5/8" and 13/16" socket sizes, which will cover Sportster, EVO, and Twin-Cam motors. Note, however, that some aftermarket "high-performance" plugs have a non-standard 18mm hex, requiring the use of a different socket. If you have difficulty finding an 18mm socket, try using a deep-well 11/16" socket.

The EconoKIT H1 and RoadTech H3 have mechanic-style forged sockets. Use the supplied adjustable wrench as the breaker bar.

For Metric Vehicles

We provide a 5/8" x 13/16" socket with most kits, which might seem odd for a metric vechicle. However, they're common sizes for many European and Japanese vehicles. The other size typically encountered is 18mm, which we don't include in any kit. That's primarily because most vehicles using 18mm are in the category requiring a special socket.

If you have trouble getting the OEM 18mm socket, try one for a Honda four-stroke dirt bike. It might involve a little trial and error, but if you have a cooperative dealer, the correct socket might be found. Bikes with easily accessed plugs, such as BMW boxers and Gold Wings, can usually use a standard forged 18mm socket, such as one offered by Sears (part number 0943330).