Champion Spark Plug D16 For Harley-Davidson

HD #3, standard heat range.
M18X1.5 thread.
1/2" (12.7 mm) short reach.
Used with a 24mm spark plug socket.
This D16 (HD #3) spark plug is the standard spark plug recommended for regular driving.
For extended high-speed driving, such as highway use, a cooler range The spark plug is available as the Champion D14 (HD #4) (MCS 931601 has a copper-cored center electrode and is fitted with the patented Ultraseal™ coated housing, to help keep the plug corrosion-free for a longer period of time).

Fits: > 750(45")/1200(74")/1340(80") Side Valve (Flatheads); 36-47 Knucklehead (61/74") (OHV) models