Parts such as the Left Cylinder Head: Bolt,flange,6x50, Dowel,pin,8x14, Bolt,flange,6x22, Washer 5mm are included in the Cx500c Custom 1980 (a) Germany / 27ps Left Cylinder Head parts fiche.
On this parts fiche the Guide,in.valve is the most specified component.
The lowest price component in this Left Cylinder Head parts-list fiche is the Screw,cross 5x8.