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Discussion Starter · #1 ·
I only realised recently that the CB350/350K2 changed from fat to skinny camshafts at some point in the production run. I also just discovered that there are two part numbers for the 'fat' cam. I guess that the K2 with the later cam, had a points cover without the 'TYPE 1' stamping but I could be wrong? Does anyone know at what date approximately that the K2 cam changed to the 'skinny' cam and how you identify the early and late 'fat' cams?

Screen shot below : ( taken from https://www.dropbox.com/s/2ohbdtqh5nvgvvf/Combined Honda_CB350_Parts_Catalog.pdf?dl=0)

Text Font Line Design Number
 

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Discussion Starter · #2 ·
Anyone have any thoughts ??? outobie?

I just stripped a lower miler CB250K0 with Hydraulic type cam chain tensioner but it has rockers with no '312' marks but has some form of skinny cam ????
 

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In the Pic I think you have reversed the Fat & Skinny Cam references.

The FAT Cams would go with the Lower Number S/N's and the 312 Rockers go with the Skinny Cams.
 

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Discussion Starter · #4 ·
In the Pic I think you have reversed the Fat & Skinny Cam references.

The FAT Cams would go with the Lower Number S/N's and the 312 Rockers go with the Skinny Cams.
That's what I highlighted in red ... I thought

Cam: 14101-286-040 Early 'Fat', 14101-286-050 later 'fat',
14101-286-060 'skinny'

Fat cams use -286- rocker
Skinny cams use -312- rockers
 

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Discussion Starter · #6 ·
I suppose as no more replies on here (bit surprised) I plan to take the three different cams I have and attempt to measure the profiles/pitch circle dia's and report back on here in due course.
 

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I wish I could reply with mire info. but you have more hard evidence to work with then I do.

The only question might be if different versions Early Vs Later of the FSM give slightly different spec's for the Lobes.
 

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Just measure the cam base diameter. Should be around 32mm for 312 rockers, smaller for the pre-312 rockers. There were rarely skinny cams with the fatcam lobes, but they exist somewhere out there. Throw the hydraulic chain tensioner away, as did honda.
Good Luck!
 
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