Parts such as the Cylinder: Gasket,cylinder (nas), Bolt,flange,6x25, O-ring,94.5x2, Cylinder Comp. are included in the Xr500 1979 (z) Usa Cylinder parts fiche.
On this parts fiche the Dowel,pin,12x20 is the most specified component.
The lowest price component in this Cylinder parts-list fiche is the Nut-wash.,8mm.