1975 Norton Commando: Our bikes

Date 24.4.2014

Presented by
  • Motorcycle Trader


1975 Norton Commando


The Norton Commando has always been an enigma. Offering an intoxicating mixture of tradition, aesthetics and function, the Commando hovered between the old and the new but was never really a modern motorcycle.

The Commando exemplified the British philosophy of continual evolution until eventual death – what started out as a 500 soon became a 600 then a 650, followed by a 750 and eventually an 850. And although Norton Villiers did its best with the final 850 Mark III, it was still an anachronism. There is only so long a design can be stretched and modified.


So what is it about the Norton Commando that makes it appealing 40 years on?

There is no realistic or justifiable reason why I like the Commando; it is purely nostalgic. Yellow police Commandos and a metal-flake, blue 750S owned by a friend dominated early motorcycling memories.

In the early 1970s, the Commando had an allure that other bikes didn’t. Not only did they look right, they were fast and handled well. Compared with the new wave of three- and four-cylinder superbikes, Nortons were lithe and minimalist. And, in 1973, the 750 Combat Commando was as fast as anything else available. So in early 1975 I took the plunge and bought a two-year-old 750 Combat roadster with just 5000 miles on the clock and a fresh set of main bearings. It also came with a 12-month warranty, something I would soon appreciate.

The first thing I learnt about Nortons was they were not ‘set-and-forget’ bikes for the uninitiated as every ride would result in one of myriad minor problems appearing. The isolastic system ensured the rider didn’t feel any vibration while riding but all the time the big, long stroke 360-degree parallel twin was shaking itself to bits.


Carburettor float bowl screws would disappear at random and one 1200km ride took 18 hours because I spent more time tightening loose exhaust flanges than riding. And if you left it on the sidestand, oil would flow from the oil tank to the engine. Thinking it was low on oil, I ended up overfilling it and blowing a head gasket. This was repaired under warranty but I’d had enough of it by then.

But my indifferent experiences were balanced by the sheer joy of riding. The engine had so much torque it didn’t need more than four speeds and, while the front disc brake was weak, the steering and handling was on par with anything at that time.

The Commando was just great in the hills and the Combat 750 didn’t give away in acceleration or top-end speed either. Over the years I missed the Commando, the difficulties now overshadowed by more positive memories. As the dollar climbed I kept looking on eBay for a suitable Commando in the US until I found one. By this stage I had narrowed the search down to a 1975 850 Mark III. After the problems experienced with the 750 Combat, I figured with British bikes the safest route would be to go for the most developed.

Although the final 850 was heavier and slower than earlier examples, it also benefited from successive generations of improvement. The Mark III may have looked similar to the previous Mark IIA, but there were a claimed 150 new parts. The isolastic motor mounts were more easily adjustable and no longer required replacement shims. Hydraulic tensioners were employed in the camchain case and an anti-wet sump valve ensured the oil would not drain from the oil tank into the crankcase.

The crankcases were stronger, and oil filtration improved. Oil leaks were claimed to be a thing of the past and the left-side gearshift and electric start also appealed. As the US received the majority of Mark IIIs and US motorcyclists tend not to ride so much, I reasoned finding a low-mileage Commando wouldn’t be too difficult. And so it was. Soon, a 4500-mile, one-owner Mark III surfaced in Colorado Springs; it looked good and the ‘Buy it Now’ price was tempting.


As you would expect from a bike that had spent most of its life in a heated basement, the photos indicated exceptional condition but the seller also mentioned an oil leak. The price was right, the exchange rate favourable and I bought it.

Several months later the Mark III arrived and initial reactions were not particularly positive. The rear tyre was flat down the centre, oil leaked from the oil tank, the standard airbox and fuel lines were missing, all the choke apparatus was missing, and the handlebar and grips were non-standard and ugly. There was a bit of work to do.

After years of working on Italian bikes, the first thing you learn about a Norton is you need a complete set of Imperial tools, and nothing is as straightforward as it looks. The Mark III exemplifies the British tradition of piecemeal development.


Factory modifications occurred over time when required without much thought going into the practicality of living with or working on it. After finding out a loose drain plug was causing the oil leak – in turn caused by a broken oil tank mount – my first task was to replace the oil tank.

Fortunately, a factory workshop manual is still readily available and an absolutely essential companion. The manual is comprehensive but optimistic in its claims about the ease of doing most things. Take the example of lining up the fastener and spacer underneath the oil tank. This process is very testing, verging on the impossible.

The next task was to return the bike to original specifications. I like bikes to be as they were when they left the factory and this meant a correct handlebar, replacement of the aftermarket braided steel front brake line, fitting of the correct choke assembly and fuel lines, and replacing the earlier peashooter mufflers with the correct black caps. It also needed a new set of tyres and I set about searching for a genuine air filter box.

Another thing you learn about Norton Commandos is that because they were produced in large numbers and were never exotic or expensive, spare parts are plentiful. Apart from the airbox, you don’t need to pay ridiculously exorbitant eBay prices for spare parts because just about everything is available new and is reasonably priced. Actually, keeping a Norton on the road is remarkably straightforward.

At Andover Norton (www.Andover-Norton.co.uk) you look at the parts book and click on the parts you need. Everything is available and arrives a week later. So I put on the set of standard Euro handlebars, choke lever, original brake line and bracket, and plastic handgrips. A new set of mufflers and brackets went on, and I even managed to obtain a genuine, brand-new seat lock. The ease at buying brand new parts for a near 40-year-old motorcycle never ceases to amaze.

The Mark III originally came with Dunlop K81 TT100 or Avon GP tyres, with Avons generally specified on US-spec Mark III Roadsters like mine. I chose the still-available Avon, primarily because the very large 4.10 x 19-inch Dunlop slows the steering noticeably, but also because Avons would have been original fitment.


Finding an original airbox was a challenge. I would later understand why these parts are so rare but, in the meantime, I scoured eBay and I eventually found one with Norton expert Skip Schloss of Flying Fish Motorcycles, Montana, US.

Most 850 Mark IIIs have had the airbox removed and this is one part you can no longer buy new. In the day it was generally removed to improve performance and most were destroyed in the process. This becomes evident as soon as you try to refit one and I’m convinced that when Norton built the Mark III it did so starting at the airbox and assembling everything else around it. Reinstalling the airbox looked like a major undertaking, requiring half the motorcycle to be dismantled.

I started by removing the carburettors – another seemingly straightforward job that turned out to be not so. According to the workshop manual, you need “a specially modified Allen key” to remove the manifolds. This actually meant a shortened key as space is tight.

With the manifolds and inlet rocker cover off, it now looked like there was sufficient space to install the airbox. Not so. Next to go was the battery tray and loosening of the oil tank. Still not quite enough space, but close. That was enough for one day. A note to Skip revealed that the airbox has to go in first, before the oil tank and battery tray. He suggested removing the oil tank, rear wheel and rear fender. This is a major undertaking. Skip went on to say, “You have a big job ahead of you but I’m impressed you want to put one of these Mark IIIs back to original.” The British are winning, but the battle continues.


More reviews:

> Our bikes: Greg Leech’s Norton Commando

> Top 5 Brits: Norton Commando

> Collectable: Norton Commando Fastback