The Camshaft / Valve assembly is constructed from several parts from which the Camshaft is the most expensive.
A sample from the products for the Camshaft / Valve include: Nut Hex 6mm, Nut,hex 6mm, Shaft,rocker Arm, Spring,valve Out.
The most reasonably priced component used on the Cb650 1980 (a) Usa Camshaft / Valve is the Nut Hex 6mm.
