Tech - Spark Plugs

Denso Spark Plugs

CC	Norton Model	Denso Plug
850cc	Commando Interstate and Roadster	W22EP-U
750cc	Commando Fastback, Commando S, Commando Roadster	W22EP-U
745cc	Atlas/Ranger P11A	W24EP-U
650cc	Dominator, Mercury ,Manxman	W22ES-U
600cc	19R, 19S, 77, 99 OHV	W20ES-U
596cc	Big 4 SV	W20ES-U
500cc	All Models 19.0 mm (3/4”) Heads	W22ES-U
500cc	ES2 OHV 12.7mm (1/2”) Heads	W22FS-U
500cc	19.00 mm (3/4”) Heads	W22ES-U
500cc	88SS (OHV)	W22ES-U
500cc	16H SV	W20ES-U
499cc	30 (OHV)	W24ES-U
490cc	500T (OHV)	W20ES-U
384cc	ES400	W22ES-U
350cc	40 (OHV)	W24ES-U
350cc	50 (OHV) Twin Navigator	W22ES-U
	Source: 2013 Denso Corporation

	Where they will fit I prefer to use the EP-U variant with the projected nose.
	"Use a spark plug that has a standard heat range. If this type of spark plug is used for traveling at low speed or over short distances (resulting in the occurrence of carbon fouling) it is recommended that you use spark plugs that have a low heat range." eg go from a W22 to a W20