There are many detail differences between the two, but who's to say that Honda wouldn't have made those changes anyway if it had stayed as a 500 (after all, they changed the 750 over the years).
I think the extra 50cc was really a marketing ploy to keep up with the opposition who had launched 550 and 650 4 cylinder four-strokes.
I've got one of each (and prefer the old 500 any day )
"I've got one of each (and prefer the old 500 any day
)"
Steve, can you tell us why?
I've got a CB500 K1 (I think) complete, or it will be after I put a top back on the engine, a similar parts bike (complete, engine case broken by ignition, but runs) and a third bike (identical to the first) mostly there except for the usual pirated items, seat, carbs and side covers. Engine seems to be OK, but obviously I have not seen it run. I also have most of 2 CB550 engines with the later clutch and transmission arrangement.
I will be reasembling the first as original and am wondering whether to use a 500 or 550 bottom end for the second. I have no idea of the condition of these 550 bottoms. Tops are off but that is another long complicated story.
They are all identical CB500K frames and running gear, so I am trying to figure which engine to build for the second one which will be a little stripped down. I'm still undecided on the final appearance.