A quirky Norton Commando 750S

George Simmonds has owned this handsome 750S Commando for 28 years – and it has some idiosyncrasies… but is still a fine ride.

Words: STEVE WILSON Photographs: GARY CHAPMAN

The long-term owner of this test Commando 750S, George Simmonds, is a very good-natured man. That is just as well, since I have to say right away that I didn’t really do his bright yellow twin justice.

George had tried to warn me that, although the engine had never been apart in his 24 years of ownership, and was a standard 9.0:1 compression ratio motor as far as he knew, it had distinctive ‘ways’, which he had got used to over time, as you do. He couldn’t be accurate on the mileage; it had had 36,646 on the clock when he’d purchased it, from Mike Coombes’ late lamented Crowmarsh Classics on the edge of Didcot.

But with a couple of reconditioned speedos fitted since then, and probably 1000-plus miles annually on average, a possible 60,000-ish mile total feels about right, well used but well looked after, with oil changes every 1000 miles, and distinctly not worn out. This is not George’s first Commando, and he says he put bigger miles on his former 750 Interstate.

The quirks

One salient oddity of this bike as purchased had been the single 32mm Amal Concentric carburettor and manifold. As standard, all Commandos were twin carb machines with a brace of 30mm Concentrics; and the only aftermarket set-up I had heard about back in the day had involved a car-type SU instrument; although today, Les Emery at Norvil says it is a popular modification.

So this was a bit of a mystery. If the intention had been improved mpg, firstly, in my experience in the 1970s and 80s, the standard consumption had never dropped below 50mpg however hard my 750 was ridden; and I had paid close attention, due to the tank that I used most being the later steel 2½ Imperial gallon Roadster one. George however, has found his set-up to be “fine till you belt it, when you’ll be lucky to see 30 to the gallon…” He qualified this by saying that he does run it on the richer side, and that you have to take into account the poorer mileage delivered by modern bio-fuel. He favours Super Unleaded, with an octane-booster additive.

George’s ‘S’, first UK registered in May 1971, although production of the variant had ceased during the summer of 1970, is a very handsome machine indeed. That’s despite lacking the S’s defining feature visually, namely the high-level exhaust system, originally mounted, stacked and splayed, on the nearside. The upswept conventional system, produced concurrently for the Mk.II Fastback and new Roadster, is more practical for his lady passenger, and looks good too.

Like many a bike over 50 years old, George’s Commando is a bit of a mixture. The frame number indicates late 1970, but the engine appears to have been substituted for one from mid-1971, over six months after ‘S’ production had ceased. Les and Sue Emery at Norton specialists Norvil (Tel: 01543 278008) confirmed this, and added that the ‘S’ in the engine number signified ‘Side-points’ (see later) rather than the ‘S’ model.

One original feature still present is, perhaps surprisingly, the S’s 2¼ Imperial gallon gas tank, in glass fibre, like the model’s redesigned side-panels. It’s finished in brilliant yellow, a colour option for the 1970 ‘S’, though normally associated with the Norvil Production racers. The paint may be bubbling now, but the tank has never leaked, and is even legal despite the 1974-on ban on the material, since it had been fitted as original equipment. George has a spare steel replacement from Andover Norton, but hasn’t fitted it as he doesn’t think it looks quite right.

So, what exactly was the relatively short-lived Commando 750 S model?

Commando S Story

Norton’s rubber-mounted wonder, commencing production in April 1968 at the old AMC factory in Plumstead, Woolwich, was a popular sensation, on both sides of the Atlantic. Its original Fastback styling appealed to many with its racer-like tail section, 0 to 60 times of under five seconds, plus long-distance capability due in large part to the absence, thanks to the Isolastics, of fatiguing vibration for the rider, at anything over about 2000rpm. Sales in North America, around 80% of Norton’s market by then, rose 25% in 1969. But the Fastback styling, though still a favourite for hard-core Norton fans, wouldn’t really do for the youth of America, where road racing was not as popular yet, and most motorcycles were pressed into off-road service for sport or leisure.

So supervised by original Commando development engineer, Wolverhampton-based Bob Trigg, redesign and restyling commenced with the rare short-lived ‘R’ model early in 1969. This kept Dominator-type silencers and bulkier side-panels, but featured, unlike the Fastback, a separate seat and four gallon tank, high bars and chromed mudguards. Meanwhile in January 1969, Norton Villiers Corp in Long Beach, California had been set up to independently market the Norton, plus AJS scramblers.

In March 1969 the ‘S’ (presumably for ‘Sports’) model had been unveiled. Norton had form with street scramblers, in the shape of the 1960s, Woolwich-built, Atlas-engined ‘Hybrid’ models like the P11 and Ranger. Combined with the Isolastic system, they were onto a winner.

Leading with the eye-catching high-level splayed exhaust system and its shiny perforated heat-shields, the bling continued with polished, naked rather than gaitered Roadholder forks, high and wide scrambler-type bars, and chromed mudguards, the rear one carrying a separate tail-light, unlike the integrated Fastback set-up. The cylinder barrels were painted silver rather than black, and the rocker box inspection caps were plated in either bright or dull finish. Smaller, triangular glass fibre side-panels gave the Commando’s midriff a more waisted profile, with the left one carrying the ignition key, while the right concealed a box-shaped five pint oil tank; though George has found that heat from the tank and its unions can be in danger of “frying the battery”, and the tank would be redesigned for 1971 Commandos.

The minimal 2¼ Imperial gallon gas tank, with a ‘Monza’ filler cap and a ‘Curly N’ transfer, crowned a lean machine. A ribbed conventional dualseat complemented it. In another part of what the training shoe industry calls “implied performance”, the chrome headlamp shell was surrounded by a chromed ‘protector ring’, to which could be clamped a mesh stone-guard – though how many ‘S’ riders went seriously off-road is debatable. But they looked as if they could. A truncated rear chainguard and plated footrest hangers continued the shiny theme.

Beneath the pzazz there had also been some significant re-engineering. On all but the handful of Plumstead-built ‘S’ machines, the former contact breakers in a rear-mounted distributor were now housed in a recess in a new timing cover, with the operating cam and auto-advance unit fixed to the end of the camshaft.

Machines thus equipped were designated as ‘Mk.II Commandos’. There had been work too on those eye-catching silencers, which were reverse cone megaphones with small outlets. Tony Denniss, another Woolwich-based member of the development team, told me that “I worked out, partly by taking temperatures in the pipes front and rear, that if you reversed the baffles, it went really well, and you still had some proof of restriction if a policeman stuck his truncheon up the pipes!” This was the basis of the ‘S’ and Roadster’s ‘peashooter’ silencers. They reduced back pressure, which did noticeably improve performance.

The ‘S’ model’s life was relatively brief, at less than a full two years, as production of it ended in mid-summer 1970, but it played a significant part in the Commando’s evolution. The model split in two directions, the first a one-year-only ‘SS’ 750, with the high-level pipes now one on either side, a smaller headlamp and a bash plate. But the main event, from Feb 1970-on, was the Roadster, essentially an ‘S’ model with a low-level exhaust system – like George’s ‘S’. It went on to be NVT’s best-seller, and in my opinion, deservedly so.

S for stall

George has had few problems with the Commando. New wheels were fitted some 20 years ago. Sensibly, electronic ignition was adopted, and when the original system conked, Boyer replaced it for free with a later version. The original speedo and rev counter have been replaced over time. A new oil pump was fitted, partly to try and counter wet-sumping issues.

The Commando’s spine frame, built by Reynolds at this juncture under the supervision of chassis wizard the late Ken Sprayson, in the early days had suffered problems with fractures around the headstock. In 1969, Sprayson designed an additional horizontal bracing tube under the tank, running back between the steering head and a mid-point on the backbone spine. This cured the problem, but later during 1970, the frame’s crossways bracing strip under the tank was moved to the bottom of the front downtubes, under the crankcase. George confirmed that his frame lacked this feature, despite its 1970 number. Perhaps older chassis were being used up during the confusing period when Commando production shifted from Plumstead to Wolverhampton and then to assembly at Andover .

It was time for us to try the bike, and George advised not to change into top before 50, and added that the clutch was “a bit sharp…” So it proved to be, to my embarrassment. The bike fired up for George with a wonderful roar, first kick every time – “I never use the choke” – but when I mounted and went to move off, the Norton stalled. This happened three times, and it was no consolation to recall that editor James had recently suffered something similar, though with a much older machine.

Finally, I got the idea, and revved the 750 immoderately as I let out the on/off clutch, so we pulled away pretty briskly. The thought of not being able to even get underway on a test bike had shaken me, but luckily from then on, the Norton’s positive points piled up. One of the 750cc Commando engine’s great features, the very strong low-down and mid-range power, was thrillingly present in abundance, and if the gearchange was a little crunchy, that could have been partly down to my anxiety to keep the revs up and not stall.

On the twisty, wood-fringed lanes the handling and roadholding, on Avon Roadrider rubber, were a delight – the nature of the winding local roads meant that I probably never got into top, but the 750 Commando experience flooded back from my own eight years of ownership, and was a delight. The front brake worked adequately, but at any higher speeds the retro-fitted 850 Mk.III disc front end that had been present on my own bike would have been welcome.

All too soon I changed down, swung the Norton round, revving furiously, tilted the willing twin into the twisties again, and raced back to George and photographer Gary. George got delegated to ride for the camera, due to my fear of stalling during the many necessary stop-and-turns. I thought the trouble in that regard might have been partly down to the single carb set-up on the Norton twins’ fine-breathing cylinder head, designed, from the Dominator SS models on, for twin instruments; but Norvil’s Les Emery told me that the many single carb conversions he has fitted had not affected performance.

George naturally performed flawlessly for the lensman, despite profound discontent at having to wear my (for him) ill-fitting open-face ‘period’ helmet. So job done, but I did regret not extending the ride onto more open roads where the strong acceleration and Isolastic-smooth ride from 60 to 90 might have been more fully savoured. But even the taster session had reacquainted me with the Commando’s muscular appeal, and proved that George’s ‘S’ was fundamentally a good ’un.