Parts such as the E-2 Cylinder Head: Sparkplug (dr7es), Bolt,stud,6x51, Rubber,sealing, Plug,spark are included in the Cb650 1980 (a) Canada E-2 Cylinder Head parts fiche.
The E-2 Cylinder Head assembly is constructed from several parts from which the Head,cylinder is the most expensive.
With twelve applications this Washer,8mm is the most specified part.