Topic: difference between R1 and R10 camshaft

[mazingerzeca]

Hello all.
I have to buy a new camshaft for a CB750 F1. The camshaft has R10 stamped on it. I have found on e-bay a CB750 K8 camshaft, which, according to partslist, has the same number that the F1 has (#14101392000), so they should be interchangeable. I asked the seller but he told me that the K8 cam that he sells has R1 stamped. Does anyone know if they are the same?
Thank you.

[Hinomaru]

Cam “R” numbers are tricky at best and cannot be relied upon for positive identification. However, If the cam was removed from an unmolested & original engine, then that’s a good bet as to being a correct replacement. Always check the engine serial numbers for additional confirmation.   

Cam part number: 14101-392-000 was used in the following engines, 1975-76 F models and 1977-78 K models. (my 75F cam is marked R2)

Cam part number: 14101-410-000 was used in the 1977-78 F engines. (my 78F cam is marked R10)

[Jerry Rxman Griffin aka MuthaF'er]

   R10
  -R 1
--------
 = R9

But seriously, that's about all that can be made of the R numbers. The general concensus it that those are just casting numbers for the blanks and have NOTHING to do with the grind.

Interchangeable - YES! Identical - only maybe. When Honda "updates" things they can supercede an old part number and use the newer item without still making both. The 75/76 F cam is supposed to be basically identical to the 77/78 K as the 77/78 K is basically from the 75/76 F bike. The cam timing is differing by 5^o. Sooooo, is that 5^o due to the grind or perhaps the sprocket?? One of the biggest mysteries about our 750's evolves around the cams. If it's a known 77 or 78 K cam go for it. If you question it then take measurements of the lobe heights and compare. One can always go to great lengths to check lobe centers and lifts at the same degrees of rotation throughout the opening profiles of both cams but that is a lot of detailed work and would only be relavent to the 2 cams that one person has in front of him.