SOHC.co.uk Forums > CB750

Camshaft - hot, cold or otherwise?

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the-chauffeur:
Looks to me like you've got a Honda camshaft and a late (F series) cam sprocket.

As Ash says, the later sprockets were drilled to reduce reciprocating weight, which is great so long as you don't want to advance/retard the valve timing.  The early models are solid, as per his other picture.  I've got a third type - an aftermarket adjustable from Cycle X.  If yours was aftermarket, it would almost certainly look like the Cycle X.  

It also seems a little unlikely you'd have a non-adjustable attached to an aftermarket camshaft.  As for the camshaft manufacture, the stamping certainly looks like it's a Honda.  In addition to the cam sprocket, I bought a Cycle X camshaft, and as well as different markings and heat treatment from Honda's, it doesn't have the timing alignment marks on the right hand end (like the ones in your photo).  Having said that, it's always possible the cam could have been reprofiled at some point, but unless you've got a detailed engine history, send it off to someone like Phil Joy or have one to do a side-by-side comparison, chances are you'll never know.

Does that help any?

honda-san:
A cam shaft with an R-- number on it is 99% certain to be a standard Honda cam. They started at R1 in '69, and the R number tends to increase as the years / models roll by. Whether the number next to the R indicates the mold/ casting / forging, or in some way relates to the lift (though I have never measured a difference in lobe height which could be related to the R number) / angles, or date range / model range is certainly not dcoumented that I have found so far. Having stripped 30+ of these engines over the years I have only ever found ONE non Honda camshaft - and that DEFINATELY did not have an R number on it.

Cheers - Chris R.

RupertB:
thanks folks - all uiseful and all gratefully received. I am being very patient at the moment and am just getting barrels and head (castings) properly checked and sorted to see if they are salvageable, and only then will I move on to valves, cams pistons etc. I could also do with an ambient temperature which doesn't threaten to freeze treasured bits of my anatomy off my body. I'm sure that applies to all of us who don't have heated garages.
So any more info will be received with interest, but updates and the like on progress will be a little slow in arriving. But have patience, they will get there.
Happy Christmas one and all by the way!

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