Topic: Cb750 Cylinder Head Dimensions

[CB750F2]

I have acquired a K4 cylinder head which I intend to fit to my F2 which has been rebored to 836 and fitted with flat topped pistons. The combustion chambers measure 22.3cc. I expected 19.5cc for an unmodified head. The valve guides are fine but the inlet valves appear to sit high in the chamber. I have some questions:
1          What is the dimension between the head gasket sealing surface and the valve cover surface? I am trying
             determine how much - if any - has been milled from the head.
2           Is there any other way to determine how much has been milled from the head?
3           As I said earlier the inlet valves appear to sit high in the combustion chamber and may account for some
              of the extra volume that I am measuring. Is there a maximum length that the valve stems protrude
              through the guides? If so what is the length?
4           I see that Cyclexchange has oversized valves - Part No ENV-16A - that can be fitted to these heads. Would
             fitting a set of these on the inlet side together with remachining of the seats be a fix. I would think that this
             would improve performance and reduce chamber volume.
I look forward to your feedback. Thanks, Pat

[CB750F2]

The Cyclexchange site has given me the answer to question 1 - 73.27mm. Can anyone confirm this? Mine is 72.3mm so it has approx. 1mm removed. Pat

[kmb69]

I just measured 2) NOS 750K heads and they both measured 72.37. Is your 73.27 a typo? Maybe your head has not been milled.

[CB750F2]

Thanks for your reply KMB. I have rechecked the Cyclex site and they say 73.27mm. I also have two heads that measure 72.3mm with a set of vernier calipers. Hopefully others will reply. Pat

[kmb69]

I think they transposed the 2 and the 3 on their website. Will check with Ken tomorrow.

[CB750F2]

Ok Thanks. I also have an F2 head that measures 72.3mm. So I have three heads - K4, 392 and a 410 - that measue 72.3mm. The chamber volumes are: K4 - 22.3cc, 392 - 22.8cc, 410 - 28.5cc. The 410 head does not look as if it has been messed with but the other two look to have some de-shrouding done. Pat

[CB750F2]

Anybody?

[CB750F2]

Bump again

[CB750F2]

Can anybody help?

[Retro Rocket]

Pat, send Mike Rieck a PM, he's the resident head guru, if he doesn't know , no one does....

http://forums.sohc4.net/index.php?action=profile;u=49

[CB750F2]

Thanks Retro. I will do that if no one else replies today. Pat

[CB750F2]

Bump again.