CHAMPION, SPARKPLUGS J12YC ( 1948-74 BT )

Champion, Copper Plus spark plug. J12YC

H-D 3-4. 14mm threaded, 1/2" (12.7mm) short reach. Used with 21mm spark plug socket. Copper-core center electrode. Spark plug comes with the patented Ultraseal™ coated shell, to help keep the spark plug body corrosion free and better looking for a longer period of time.

Fits: > 48-74 B.T. (NU)