Topic: Need early 750 F motor info.

[754]

Found this in my stuff serial # starts with 25 and ends with 799*

 Does/should it have same cam and valves as a K model?

 Does/should it have a mark on back of head like 77/78?

[Jerry Rxman Griffin aka MuthaF'er]

Frank,

Give me the full serial number please. PROBABLY has same valves but different cam. What number is on the back top head fin by #3?

[754]

The missing numbers are all zeros.. I forgot to look at the head its still wrapperd up, got to move some stuff around it. Has spigot exhaust, but those may have been added.
So it looks like it just under 8K  serial number.

[bryanj]

According to my ID book starting 250 makes it a 1975 CB 750 Super Sport (CB750F0)

[Jerry Rxman Griffin aka MuthaF'er]

CB750E-1007999 is 1975 or CB750E-2007999 is 1976 ??

That and get me the head info and I can give you the info you're looking for. If it's a 392 head it will have better combustion chambers and the ports may be done better too from the factory. The compression is 9.2:1 also, up from 9.0. 

[754]

 its  CB 750E2507995
 head is marked X 3 and has the oval logo before that.

[Jerry Rxman Griffin aka MuthaF'er]

Frank, I stand corrected. Just got mine back this afternoon. CB750E-2501954. I was thinking serial numbers. Mine is an early 1975 build date of Jan 75. Yours would be build date of Feb 75 in all likelihood. They went to serial #15054 through 3/75 before switching over to the 76. I was looking for "392" in that spot on the head to confirm it is a true 750F head. If it's not a 392 head the chambers will probably show shrowding inside the chambers as opposed to a more hemi look of the 392. 77K/78K also use the 392 head but 78K has stronger 77F/78F springs and keepers and the keeper slots in the valves are different. Cam will be impossible to visually tell. If it were a true intact F engine then I wouldn't doubt the cam. Big difference in the F cam and the K cam of that same time frame. Valves should be 31mm and 28mm whether it's a K or a F head unless it's the F2/F3 head.