Genuine NGK B8ES spark plug. Buy one or buy a box of 10 and save money. We carry them for the Honda MT125, MT250, MR175, MR250, CR450R and SL350 but there are many more applications for the B8ES.
1981 CR450R (but best to use B8EV, B9EV or BR9EG for racing)
1965-1974 CB450, CL450
1968-1977 CB350 CL350 CB350G CB360 CB360T CB360G CL350 CL360 CJ360T