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A technical forum for Commandos

oil filling primary cover


engine oil tank level just below top mark and primary oil filled to just below level did about about 130 mile round trip , check oil tank and level just above low , checked primary chain and oil poured out of level screw , the primary side oil seal has gone with engine oil filling primary side . Replaced seal twice now and seals look okay < no damage to see > but cant understand why this is happening , have breather on inlet rocker cover and RGM one way breather valve on engine breather to tank .

Dave Taylor head steady


I'm hoping that someone can help me out. I have fitted the head steady and love it but the spring has now broken twice. My question is is the spring needed or should I chuck it. I followed all the installation instructions regarding the tensioning the spring

Thanks in advance


Ignition timing


I have just completed my Commando rebuild with Boyer ignition, Alton Electric start and Mikuni single carb.  The bike started first touch.  Tried to dynamical time it today and despite retarding the timing as far back I can it is still showing it is too advanced at 35 degrees compared with 31 which is in the Boyer instructions at 5000 rpm. The issue seems to me to be that with only one location spigot on the Alton chain case the timing arc on the chain case can be changed significantly as the chain case rocks up and down. Has anyone else found that they can’t retard the ignition enough?

Help info needed


Can anyone tell me what this is it came in the packet you see and  I am sure the markings are original I own a  1975 Mk3 Commando but cannot be sure i ever got this for it, it may have come with the loose parts I got with it but again cannot be sure, does anyone know the company markings and where they can be contacted and see if they have info relating it appears new and unused many thanks Chris

Front tyre size and load rating


Hi All,

This could turn into something close to asking what oil to use but here goes...

I was asked the question about tyre size and load rating for a Commando 850 Interstate MkIII. Personally I have Avon RoadRider MkII front and rear with the front being a 90/90-19 54V and the rear a 100/10-19 57V. I prefer the thinner section front tyre as is seems to improve the handling and less propensity to follow the white lines.

Now looking at the load ratings:-

54V = 212Kgs @ 149MPH (I wish)

57V = 230Kgs

Carb help


I have been struggling to get my 1974 850 mk2 to tick over it was fine but the rh carb was flooding so i decided to strip both 932 amals down and fit new stay up floats while i was at it i fitted new float valves,needles and needle jets cleaned all internals and blew out with compressed assembled and fitted and the bike fires up ok with a few pops and splutters, i have fiddled around with the air screws and throttle screws but cannot get it idling right.I dont realy know what i am doing and need help.I live in Congleton cheshire and wondered if there is a member within striking dista

New to the Commando - a big thank you to Peter Shand


I've recently acquired my first Commando ('74 850 Interstate) and am getting to grips with the joys of working on old bikes for the first time in a long while. I just wanted to extend my thanks to Peter Shand for all his help today, both sorting out the front m/cylinder, but also for his insight into everything Norton, and giving me an inkling of what I might have let myself in for! It was a joy to watch him at work - many thanks, Pete.

His email is - thoroughly recommended.


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