Topic: Will a 72 cb500 head work on a 75 cb550 motor?

[dergs713]

Had some issues w a bent cam it looks like, and trashed the races on my head... i have a head of a cb500 that's in good shape. Will this work? The cb550 bike is a 75. The cb500 head is out of a 72 I'm pretty sure. If that make any difference.
Matt

[Reganator]

Hopefully someone that knows 100% for sure will chime in, but here's my .02:

Lots of parts are interchangeable between the 500 and 550, including the whole top end cylinders and all apparently.  Now, I can't guarantee that the heads alone are interchangeable (or at least in the direction you are going) but since the max overbore on a 500 is something like 72.72 mm my guess is that this would more or less end up like a an over bored 500 with a 550 bottom end.  Again, I'd wait for those who know for sure to chime in but from what I see it sounds like it would work out just fine.  Head gasket may be an issue though.