Parts such as the Clutch ('79-'81 C2/c3/c4): O Ring,7mm, Ball-steel,3/8, Rod-push,clutch Sprin, Bolt, Clutch Spr Fitt are included in the Kz1000c4 Police 1000 1981 Usa Canada Clutch ('79-'81 C2/c3/c4) parts fiche.
In this schematic the "Ball-steel,1/8" is used most often.
The most reasonably priced component used on the Kz1000c4 Police 1000 1981 Usa Canada Clutch ('79-'81 C2/c3/c4) is the Ball-steel,3/8.