Champion, Copper Plus spark plug. D16 750(45")/1200(74")/1340(80") Side Valve (Flatheads) 36-47 Knucklehead (61/74") (OHV) model

H-D 3 standard heat range. M18 X 1.5 threaded. 1/2" (12.7mm) short reach. Used with a 24mm spark plug socket. This D16 (H-D 3) is the standard recommended spark plug for regular riding. For extensive high speed riding like extended highway use a range colder spark plug is available as Champion D14 (H-D 4) (MCS 931601). Spark plug has a copper-core center electrode and is equipped with the patented UltrasealT coated shell to help keep the spark plug corrosion free for a longer period of time. 750(45")/1200(74")/1340(80") Side Valve (Flatheads) 36-47 Knucklehead (61/74") (OHV) models (NU)