Parts such as the Camshaft / Valve: Nut, Tappet, Nut,hex 6mm, Spring,valve Out, Valve,inlet are included in the Cb550 Four Cb550k3 1977 Usa Camshaft / Valve parts fiche.
The component with the lowest price in the CAMSHAFT / VALVE schematic is the Nut Hex 6mm.
The most expensive part in this assembly is the Camshaft.