Reviving a Norton

Recently a badly neglected 1975 850 Commando Mark III found its way to my garage. The bike hasn't been run in over 25 years and spent several outside. The plan is to rebuild it as a runner, in a mildly modified form that will be mostly stock and will not preclude a return to "stock" at some future date.


Yes the bike has been modified by the original owner. The frame has been braced, the twin carbs have been replaced by a single Amal and the electric start is long gone. Additionally the friend who I bought the bike from tells me that hi-lift cams have been installed and other work done to the head.



A look into the cylinders and exhaust ports with a borescope, shows that at minimum the head will need to be rebuilt and the cylinders honed, with new pistons and rings installed.

I'm documenting the rebuild in a blog, Reviving [a] Norton (http://revivinganorton.blogspot.com), comments, suggestions, words of wisdom and encouragement are appreciated either here or at the blog. I expect I'll be drawing on the collective wisdom and experience of the group.

Jim

I'm kinda digging the gold bits!
I wouldn't mind seeing some better pics of the frame mods.
Oh, another member of this forum (hobot) also calls his norton "Trixie".

Interesting frame ya got there, hope to see it in the raw to understand what was done. Interesting the fella would put a big ass single carb on a hopped up cam. Goes against the go fast crowd, but for my own experience enjoying a bigger single than the duals. Do you have plans to retain the carb?

hobot said:

Interesting frame ya got there, hope to see it in the raw to understand what was done. Interesting the fella would put a big ass single carb on a hopped up cam. Goes against the go fast crowd, but for my own experience enjoying a bigger single than the duals. Do you have plans to retain the carb?

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Now that the tank is off, I'll take a couple of pictures of the frame mods. One thing that I found is that the tank rubbed near the front and some rubber, rub strips were taped to the frame to isolate the tubing from the tank. One early decision that I need to make is to whether I leave the frame as is, or return it to stock condition, if that is possible.

I haven't made a firm decision on the carb and this is an area where I'd like to hear pros and cons.

Jim

The tank had some rubber pads to keep it off the frame, as standard.

Be interesting to try those frame mods, to see how it rides, before removing them.
PO obviously put quite some work into them...

If the carb was setup to the running stage, also be interesting to try it.
Looks quite large ?

The set up seemed to have pleased someone and there's 1000's and 1000's of the ordinary Commandos so I'd sure try it as 'designed' and to watch the double takes of Nortoneers seeing it.

welcome sleeping dog, I'll be watching for your posts with great interest since I too hace a 75 MKIII that I'm bringing back from a long slumber. Lots of good folks here on this site with tons of help available to you. Cj

Sleeping Dog said:

I'm documenting the rebuild in a blog, Reviving [a] Norton (http://revivinganorton.blogspot.com), comments, suggestions, words of wisdom and encouragement are appreciated either here or at the blog.

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By the way, there are 18,847 miles on the bike

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The "Green Globe" speedo isn't the original, it should be a matching "NVT" item, so the mileage figure is not likely to be accurate.

Did Euro & UK bikes have different tail light assemblies?

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No (although there were two types of rear lens, one had side reflectors, the other did not).

Frame Bracing

There were a couple of persons interested in learning more about how the frame has been braced. The following photos should help.

First we need permission from Cletus the shop foreman.


From above looking forward.


Side


Upper steering head brace



Lower frame


Jim

Wot's STOCK .

I think it might be a bit modified . :? besides the extra bits , theres bits thats not . So youve a liscence to go as you please .

Someones gone to a lot of trouble to set up the whole top tubes / isolastic arangement .So youre not going to get it back to ' STOCK ' in a few simple steps
unless its swap the whole cabodle of mods as a package for the standard set up . Bet thered be a queue too .

Possibly best to clean & fire up , as is . See what you make of it , and take it from there . At the moment its a fairly unique piece of equipment,
and youd have to presume the guy had a fair idea of what he was up to . So untill proved otherwise deviating from its current build would be fiddling
perhaps to no good effect .

Useing the powertrain & other bits in a replacement frame if you prefer a standard appearing machine is what youll be in for . No hurry ,
the world will still be here tomorrow .

Rohan said:

The tank had some rubber pads to keep it off the frame, as standard.

Be interesting to try those frame mods, to see how it rides, before removing them.
PO obviously put quite some work into them...

If the carb was setup to the running stage, also be interesting to try it.
Looks quite large ?

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There may have been rub pads, but probably not ones like these.



hobot, keeping the frame as is reduces a certain amount of work.

L.A.B., thanks for the info on the speedo & tail light.

Jim

P.S. theres some ' runner ' length in that intake manifold , so it should work pretty good . The Mk II Amal there isnt a bad carb . Do you know the bore size ?
Thinking 34 mm plus . more plus the better . 40 would be ok .

Looks like someone had a 'better idea' than NV? Hmm.

Dave

If I remember correctly the top frame loop and head brace is not unlike the Featherbed set up.

Head fin extensions look quite well done, was wondering why it looked different. That IS a lot of work. Was the builder trying to replicate aspects of the Featherbed frames?

Keith1069 said:

Was the builder trying to replicate aspects of the Featherbed frames?

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I wondered that too.
With the alterations it doesn't look overly robust around the headstock to me, the featherbeds have a bolt in headsteady that triangulates that area quite well.

The other day I had a couple of hours and continued the dismantling of the Norton. Most of this involved removal of the electrical, so much marking of wires and note taking transpired. Often when I come across a vehicle of interest or a piece of furniture, my eyes are drawn to how it is joined together. If it is furniture, are the drawers dove tailed, hand or machine cut. How are the corners of the cases joined, etc.

For restored automobiles, it is how do the panels fit, are they level relative to the others and are the gaps uniform. On motorcycles, it is the welds of the frame. Up till now I've mostly looked at Trixie from the point of view of what the bike needed and what I want the finished product to be, but as I spend more time with the bike, I'm seeing and learning more about it.

I'm impressed by the quality of the welds where the frame was modified, the builder was skilled.




Jim

You can rest with all assurance that you won't ever park next to another one like it.

Pretty neat...

(I thought he had modified a turned-around Triumph head for just a second there)

I thought the fins looked weird on the head too. They are bigger.
That thing is really cool. I like the modifications and would not change a thing, just redo it and see how it works.
Interested to know whats done to the engine internally.

Is this likely to be the only Commando you will ever own? You will put a lot of work into getting that bike going and a fair bit of money. Most of us will not be able to give you any advice on problems you encounter because of the custom one-off build. It means you will be solving any geometry problems yourself and are basically designing a motorcycle from the ground up. If it doesn't handle well when finished, the frame will be suspect, despite the fact that it might be something else. If it were me, I would find a straight frame, build a stock or reasonably close to stock bike and I would keep that frame as a collectible. Just my two cents. But I think it makes even more sense to get a stock frame if you think you might want to one day sell the results of your efforts.

There are a few members on here who have a lot of experience with Seeley frames and Featherbed frames. If nothing else, get the frame stripped down. Take a lot of photos and measurements and then get some advice from people who know frames. Maybe put the frame in the back of the truck and go visit NYC Norton.

You gotta wonder why this bike sat for so many years if it was a good idea to start with.

Russ