Topic: Is the 72 CB500 4 an interference type motor?

[Bobarama]

Need to know if a hanging open intake valve would be contacted by a rising piston.

[dave500]

if its hanging very slightly because its sticky maybe ok,if the cam chain snaps youll bend valves so technically its an interference type engine.

[Bobarama]

Thank you that's the information I was looking for my bike has been sitting for about 20 years and when I turn it over the tappets come up Val follows but at the very end they snap shut just the four intakes the exhaust move fine guess it's just from sitting a long time. I soaked the top end down real good with Marvel Mystery Oil come this weekend I'll try turning it over a little bit more and see if it helps out.

[HondaMan]

You can pull the head of the 500 right in the frame: at the very least, I'd recommend that approach. You can them fix up the valves easily.
When reassembling: get some slightly thicker O-rings for the 2 outer oil passages, because the new head gasket you will get (anywhere) is thicker than the old one, and this will cause oil leaks at those O-rings.

...just one of the 'tips' coming up in my new 500/550 book...