Champion, Copper Plus spark plug. H8C

H-D #4. 14mm threaded. 12.7mm (1/2″) Short reach. Used with a 21mm spark plug socket. Copper-core center electrode. Spark plug comes with the patented UltrasealT coated shell to help keep the spark plug body corrosion free and better looking for a longer period of time.
54-56 KH 57-85 XL (NU)
Sold as: 4