I have heard all sorts or reasons why Honda changed the clutch push-rod after K0 models E/No. 1018727 on the CB500 four, from a solid steel part (i.e -292- from the CB450K1) to a 500/4 specific ---323--- part , which has both alloy and steel sections (also used on the CB500T model).
My latest theory is that when the chain snaps etc, the later one easily breaks at the alloy part of the rod thus minimising the damage in the drive sprocket area, rather than trying to bend the earlier steel variant and cause more serious damage.
