Designed to fit perfectly with the clutch hub lock nut. Honda CB 750 K Z RC01 RC01-2000121 RC01-2032973 1978 4 77 BHP, 57 kw. Honda CB 750 K Z RC01 RC01-2000121 RC01-2032973 1979 4 77 BHP, 57 kw. Honda CB 750 K A RC01 RC01-2115751 RC01-2118618 1980 4 77 BHP, 57 kw.