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Thru Camshaft Breathing

Norton Models (not Commando or P11)

Thru Camshaft Breathing

Postby robs ss » Sun Sep 03, 2017 5:34 am

During an idle moment I decided to check if the internal bore of the drive side of the camshaft of my 650SS in case it might be partially obscured with build-up, etc.
First I tried blowing into it, from the drive end - no luck, it seemed to be totally blocked
No problem I thought so I tried digging into it with bamboo cooking sticks but found it was still blocked
"Well I'll drill that crap out" I thought and started with a 3/16" bit
I was concerned when metal swarf came out so shone a torch down it only to find... it was completely blocked with solid metal - never was hollow from the DS lobes to the "breathing" holes
No wonder "cam breathing" Nortons have such a bad reputation for leaking oil!
I wonder how many other 88s, 99s, Manxmen, 650ss, Atlas and Mercuries out there are suffering from leaks thinking their breathers are working???
I am going to fit a breather (a la Jim Comstock) at the lower rear of the crankcase but thought I'd let others know what I'd found
Photo of the cam ID below
Cheers
Rob
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1964 Norton 650SS
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Re: Thru Camshaft Breathing

Postby APRRSV » Sun Sep 03, 2017 1:11 pm

Were any of them hollow for the full length? I thought they breathed through radial holes near the breather end.

Ed

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Re: Thru Camshaft Breathing

Postby robs ss » Sun Sep 03, 2017 1:45 pm

You're correct Ed
Mine is not hollow, however, from those radial holes to the breather (LH) end, as it should be - so could not have ever breathed
Cheers
Rob
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Re: Thru Camshaft Breathing

Postby robs ss » Sun Sep 03, 2017 3:29 pm

Ed
Re-reading my original post, by "drive end" I meant engine drive side not cam drive.
Sorry if I caused confusion
Cheers
Rob
1962 Norton ES2
1964 Norton 650SS
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Re: Thru Camshaft Breathing

Postby APRRSV » Sun Sep 03, 2017 3:43 pm

Hi Rob,
That is what threw me off. No problem. I'll need to check the new camshaft for my G15 build. This info is definitely a good heads up.

Ed

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Re: Thru Camshaft Breathing

Postby BritBikeBoy » Sun Sep 03, 2017 5:30 pm

Interesting, thanks for sharing that info Rob.

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