Topic: Head/motor capatibility - CB750

[markusarealius]

Good evening all,
Can someone please give me some guidance on what i can use.  I recently bought three CB750 motors including all the parts except for the topend on one case.  Here is my situation.  I would like to build one utilizing the best of all the parts. The case numbers are: 2244743, 2381401, 2526775 -- the best looking of the three is 2526775 and this one is the one that I would like to complete.  There are only two heads and jugs with the parts i bought, I just can't tell which one of the two would go with the case.  The previous owner said the two jugs, heads, and valve covers come from the cases but he couldn't remember which went where.

Is there a place on the heads, jugs, or valve covers that would tell me which case they would fit or go with?  Also, if you know which motors I have or have suggestions on which ones would be the best to rebuild I am open to suggestions.
Thanks,

[Jerry Rxman Griffin aka MuthaF'er]

2526775 looks to be a 76 CB750F. Probably the best performance wise. Look for a head that has "392" on the top inside fin intake side by #3. That would be the match. You'll probably then notice that the combustion chamber is a more hemi shaped without the higher ridges around the valve/plug hole. 

[markusarealius]

Just spent the last ten minutes looking for that "392" -- In the center of the head I see an "X" and a "3" but I could find any numbers other than that, and on the other head I found just a "2".  In the process i dropped the one with the "X" and "3" and broke one of the intake couplings (where the rubber boot attaches to the head intake) does this piece screw out?  It looks like a big nut that might screw out.....lol, maybe the other intake will work if I screwed that one up....

[Jerry Rxman Griffin aka MuthaF'er]

If you have the head that came off a 75/76 750K or a 77/78 CB750K it should have "392" on the top fin intake side next to #3 on the middle side. I'll attach the picture of my original head from my 75 F. My 78 K head has 392 but it looks different and had K8 hand stamped next to it. Not sure if that hand stamp is standard but the K8 version did use different/stronger springs and keepers.

[markusarealius]

Jerry,
Both heads that I have do have that little symbol in your picture below and have a number on them in the same spot as the 6 in your photo.  But neither of them have any number between.  I am pretty confused.  I did find out that the intake insert will screw out so it can be replaced -- the bad news I still don't know what heads I have, they may not even go to any of these cases.  Is there another place they might have numbers or identification?
Thanks,
Mark