I owned Honda CB 350s ( 2 )and a CB 750 k3 all from the 70s Only the engine/transmission contained aluminum. Frame, tank etc were steel.
Lots of painted aluminum on that bike - a 1986 Nighthawk S, like mine. The amount of aluminum on bikes would increase as time went on as the sportbike power and weight wars went on. Most of it would end up clearcoated or painted black at the factory. And the paint didn't fall off it.