Parts such as the Right Cylinder Head: Guide,ex.valve, Washer 5mm, Ins,r,carburetor, O-ring.8.7x1.8 are included in the Cx500 1979 (z) Usa Right Cylinder Head parts fiche.
On this parts fiche the Guide,in.valve is the most specified component.
Of all the components used in this assembly the Head.r. Cylinder is the most expensive.