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A technical forum for all single cylinder Nortons

OHC Cambox single knocker



I am building a 500c OHC engine from parts.

The cambox which I intended to use is in great condition but it was fitted with smaller diameter rockers ( the pivot area where the cork washer goes.) Can anyone identify which year or engine this was fitted to and are there any rockers available?


Thanks Philip


Fitting a sidecar to a Big-4 Assistance requested.


I am posting this on behalf of a new member. Peter Craig.


I'm a new member and have just restored a 1952 Big4 that I used to have attached to a sidecar as a 16 yr old in 1964. Unfortunately the sidecar was not kept under cover.

I have acquired another sidecar, but i am having difficulty finding the right fittings - particularly the one for the back hole at the rear wheel - as shown on second pic from another bike.   Appreciate any suggestions/help to get the job done. Finding parts and / or setting up the sidecar.

Thanks, Peter


Model 18 kick start spring



I am currently installing a new kicker spring and was wondering what is the correct slot to put the tab into? I have a slot at 12-3-6-9 o’clock as looking at it. The previous owner had installed at the 3 o’clock but it would not recoil worth a crap.   


Model 18 Cam Follower Profile


My 1931 Model 18 has worn cam followers. These are the radius type and the wear is causing the valve open duration to be extended due to the change in position of the cam to follower contact point. I have sent the cams and followers to Newman Cams for reprofiling. Ken Newman has asked me if I can supply a drawing of the follower, or a good example so that he can recreate the correct radius. Does anyone have information on the follower profile, or a good example follower that Newman could copy?

Many thanks, Ian McD

Model 18 top end


Hi everyone. Iam going to take the cylinder head off to decarbon and have a look  at it has its leaking oil on head gasket. Where it the best place to purchase a top end gasket set for 1948 model 18?

Also what are torque settings for the rocker box bolts and cylinder head ,

Regards Paul Bennett 

Laydown gearbox selector bushes



On my 1954 ES2 I’ve been having gear selector problems, so have stripped and removed the gearbox from the frame as the bush for the quadrant arm leaks oil.  When I stripped it down I found that the quadrant was rotating on the spindle, rather than the spindle turning in the bush. 

1954 Norton International Model 30 - help with a few questions please



I'm new to the club and would like help with a few questions regarding a 1954 International Model 30 please. I'm in the process of buying it, but just doing a bit of due diligence.

The frame is brazed and possibly a Clubmans version. How would I tell if it is? I've searched on-line and can't find an answer.

The engine and frame numbers are not matching. How will that affect the value of the bike?


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