Topic: 72 CB500 cylinder head question

[jacksonrpower]

Hi I am currently rebuilding a 72 CB500 and I cracked a bracket on the cylinder head. I bought a new 71 cylinder head off ebay thinking it would fit but I noticed something very different about it. These holes between the valve spring are not on the 71. What are they? Are they necessary?

[Kenzo1979]

Yeah, the '72 part you have (Which I think is actually off of a '76+ 550) was an improvement where the holes you're speaking of had dowels or bolts or something that kept the rocker arm shafts from rotating, therefore keeping them from wearing out faster.  I think your PO upgraded this piece and you are now in the process of retrograding.  I have a '71 500 and a 74' 550, so I've never physically held the other style, but I do know this because there is a mod  somewhere around here  that tells you how to remedy this.  As far as I know, all of the 500's had this style and up to the early '76 550 did as well. Here's one thread on this, and if you search there are more:

http://forums.sohc4.net/index.php?topic=89280.0

[bryanj]

Kenzo is talking about the rocker cover, if you mean those big holes they are to get axcess to the cylinder head nuts and have rubber pucks over them to stop oil leaks!!