The Oddball Norton 750 Commando
By Robert Smith
Engine: 745cc overhead valve, two valves per cylinder, air cooled parallel twin/56hp @ 6,500rpm (R model; 60hp @ 6,800rpm)
Bore and stroke: 73mm x 89mm
Compression ratio: 8.9:1
Carburetion: Two 30mm Amal Concentric
Electrics: 12v, coil and breaker points
Frame: Twin downtube cradle with Isolastic engine mounts
Front suspension: Telescopic fork
Rear suspension: Twin shock absorbers, adjustable preload
Front brake: 203mm (8in) twin-leading-shoe drum
Rear brake: 178mm (7in) single-leading-shoe drum
Front tire: 3 x 19in
Rear tire: 3.5 x 19in
Wheelbase: 1,441mm (56.75in)
Weight (dry): 181.5kg (400lb) (approx.)
Seat height: 787.5mm (31in) (SS; 800mm/31.5in)
Fuel capacity: 9.5ltr (2.5gal) (SS; 8.7ltr/2.3gal)
Top speed: 115mph (est.)
If market demand is today’s mother of invention, then opportunity is its midwife. Such was the case with the “R,” “S” and “SS” models of the 750 Commandos.
The late Sixties were a tough time for the British motorcycle industry. Buyouts and mergers were happening left and right, yet despite being the illegitimate child of a shotgun marriage between Associated Motor Cycles and Villiers, the Norton Commando became one of the most successful motorcycles ever produced in Britain.
Best known are the Roadster and Interstate models, built starting in 1971 until production ceased in 1975. But between the first Fastback Commando of 1968 and the final electric-start bikes of 1975, the factory built a number of short-run variants that are now highly collectible.
The R and the S
The earliest Commandos were made at the old Matchless factory in Plumstead, South London. When the Plumstead site was slated for redevelopment, assembly was moved in 1969 to a new facility in Andover, Hampshire (on the famous Thruxton circuit), while engine manufacture went to the Villiers factory in Wolverhampton, West Midlands.
Along with the change in location came an opportunity to tidy up the Commando engine. Principally, the ignition points were moved from a chain-driven jackshaft behind the cylinders (where the magneto had been on the 750cc Atlas) to the end of the camshaft to simplify the design and make the points easier to service. The tachometer drive, previously taken off the end of the camshaft, moved inboard, with the tach cable now coming off the front of the engine instead of the right side. The new Wolverhampton engine became know as the 20M3S, while production of the old 20M3 “jackshaft” engine stayed temporarily at Plumstead pending the plant’s closure. (The numbering scheme works like this: the 750 twin engine was Norton’s Model 20, and the Commando engine the Mark III version; hence 20M3.)
The fiberglass bodywork and general styling of the original Fastback Commando, while distinctive and racy looking, was somewhat unconventional, and wasn’t as popular as the Norton folks had hoped. So to boost sales for 1969, two new models were introduced: The Commando “R” and “S.”
The more conservative R model was in essence a transition model from the Fastback to the Roadster. It used up the remaining 20M3 engines, with the side-mounted oil tank and sausage-shaped mufflers from the Fastback, but was fitted with a stylish new fiberglass gas tank and a conventional dual seat. All R’s had gray side panels regardless of gas tank color.
The S, however, made a radical styling statement. Its 5in headlight wore a chrome “halo” attached to a special upper steering yoke, and side panels, color-keyed to the metalflake-painted fiberglass gas tank (the same tank as the R model and later Roadster), covered a central oil tank. Gone were the sensible shrouds and gaiters from the front forks, exposing slender chrome fork tubes with token dust excluders. Chrome exhaust headers wove around the frame downtubes, exiting on the left and sweeping along the side of the bike, with chrome heat shields adding a finishing touch. Chrome also anointed the fenders, rear damper shrouds, chain guard and seat trim. Gaudy, maybe — but subtle it was not.
The R model ended with the final closure of the Plumstead factory in 1969, but the S model lasted into 1970.
For 1971, the Commando range expanded to six models: The Fastback, as before, but now with the 20M3S engine and upswept exhaust; the Fastback LR (a Fastback with a larger “Long Range” gas tank); the Roadster (essentially the S model with low pipes); the Production Racer, a full-fairing version of the new Roadster; the chopper-esque Hi-Rider designed with the American market in mind; and for three months only, the Street Scrambler SS.
I’ve met Norton collectors who have never seen an SS. None of the standard reference works carry any photographs, and details are sketchy. Perhaps trying to emulate the earlier success of AMC-Norton’s P10 desert sled, the SS was right on styling, but way too heavy for serious off-road work. It combined the basic Commando engine and cycle parts with a new, smaller “peanut” fiberglass gas tank, abbreviated dual seat, sprung front fender, smaller headlight and braced motocross handlebars. An elegantly curved waist-level exhaust pipe ran along each side of the bike, terminating in a “peashooter” muffler.
But the days of the Street Scrambler were over almost as soon as they began, especially at the “heavy” end of the spectrum. Not for the first time, a British bike maker had misjudged the U.S. market, especially in fashion conscious California where most of the SS models were sent. To salvage sales, dealers removed the dated scrambler parts, converting SS’s to Roadsters. By this time all Commandos were identical from the steering yokes down, different models identified by gas tank, seat, handlebars, exhaust and side panel changes. Swapping parts to make a different model version was easy.
In motorcycling, 15 minutes of fame are equivalent to one season in the sales brochure. The R, S and SS models lasted barely all of that. But each made a valuable contribution to the Norton Commando’s unlikely and remarkable eight-year production run.
Taking advantage of a rare opportunity to view all three models, I met Tony Duffett, Jim Bush and Dave Guthrie, owners, respectively, of R, S and SS Commandos at Wendell’s coffee shop in Fort Langley, British Columbia. Parked next to each other, the family resemblance appears strongest between the S and SS, both exhibiting a North American styling influence. The R styling harks back to Nortons of the early Sixties, the mufflers being identical to the Atlas built during that decade.
Tony Duffett found his R model as a basket case, advertised in a local Buy & Sell paper. His initial survey of the machine concluded that it must be a 1969 Roadster. Ah, but there was no such thing, retorted Vancouver Norton expert “Redline” Dave Sundquist when Tony reported his find, adding that it had to be either an R or S model as the Roadster wasn’t introduced until 1970. “Dave said if I didn’t buy it, he would,” adds Tony.
The restoration went fairly smoothly, though Tony did have trouble with the rider’s perch. “The bike was pretty complete when I got it. The most difficult part was sourcing the correct seat.” The outrageous gas tank paint is as close a match as possible to the original “Fireflake” red.
Jim Bush’s 1969 S model was rescued from an abandoned chopper project. The most difficult parts to find, says Jim, were a usable centerstand, the correct silver metalflake tail light housing with Lucas reflectors, and the plastic trim caps for the front fork pinch bolts: The last items are still AWOL.
Jim’s fastidiousness for originality extended to retaining the less-than-adequate, frame-mounted, tubular center stand and the direct-drive rear hub. (Later Commandos have three rubber shock absorbing pads in the hub.) Jim admits to a small number of deviations from stock: the aforementioned trim caps; flexible plastic rocker oil feed replacing the crack-prone stock steel lines; vernier-adjustable Isolastic mounts; improved rear muffler mounting; extra gusseting on the frame seat loop; and a 3.25in front tire in place of the now unavailable 3in type.
The restoration took just three months — though Jim spent more than 10 years accumulating the right parts!
Dave Guthrie nearly lost his SS before he even bought it. When he saw a 1971 Norton advertised locally, he followed up right away knowing other members of Vancouver’s British Motorcycle Owners’ Club (BMOC) would also be on the trail. Dave was in the middle of haggling with the owner when he heard a car door slam and footsteps approaching. “OK, consider it sold,” Dave said, agreeing to the full asking price. “Just then, two guys from the BMOC walked around the corner. It was probably the last under-$1,000 Norton basket case in the area,” he says.
Restoring the SS was a challenge. The bike had been stored in a chicken coop. “It was covered in feathers and chicken s***,” says Dave. On the way home with the bike, and still unsure of what he had, he stopped at a car wash and hosed the bike down, becoming aware for the first time that the exhaust pipes dragging on the ground should have been at knee level. A check into a 1971 Norton sales brochure revealed the truth: Dave’s bike was an SS, one of only a very few that have survived intact.
While each of these unusual Commandos had its place in Norton’s lineup when produced, they seem to have long since been forgotten by all but the biggest Norton fans. Nonetheless, they were important to the ultimate success of the Commando line, and serve as reminders of Norton’s marketing creativity in a time of limited capacity.
It’s in the rubber: Norton Commando Isolastics
The Commando story begins in the mid-1960s. Industrialist Dennis Poore has just acquired the bankrupt AMC Motorcycles and its top brand, Norton. Norton’s flagship model, the 750 Atlas, is aging badly. Its overstretched, long-stroke engine is a vicious vibrator, especially in the lightweight, dual-cradle “featherbed” frame, designed originally for the racing Manx single.
Poore’s first project is a new big bike for the American market. Poore decides to revive the 800cc overhead-cam Norton P10 engine, developed and abandoned some years before. Dr. Stefan Bauer, whom Poore lures from Rolls-Royce, proposes using the P10 engine in a new frame of his own design.
Vibration is verboten, so to this end Bauer decides to isolate the power unit with rubber mountings. To avoid transmission snatch and chain windup, he fixes the swing arm to the engine unit, separating the entire powertrain from the frame — and hence the rider. He calls his system Isolastic. It’s brilliantly simple, and vice versa.
But the P10 engine is shelved, and for good reason: It is complex (the cams were driven by one long timing chain running through tunnels on the outside of the engine), expensive to make and — critically — less powerful than the 750 Atlas.
Faced with an urgent need for a new bike, Norton’s Bernard Hooper, in an inspired piece of lateral thinking, suggests putting the old Atlas engine in Bauer’s frame. OK, says Poore, build it — adding that it has to be ready for the 1967 Earls Court show in London, just three months away.
But Bauer designed his frame around the unit construction P10 engine, where the swingarm could be attached directly to the power unit. Part of Hooper’s dilemma is that the separate Atlas engine and gearbox first have to be mounted in a sub-frame to which the swingarm can be attached.
Hooper, an experienced development engineer, and his assistant Bob Trigg set to. They make the show — just.
In Hooper’s Commando, rubber buffers are enclosed in two cross-frame tubes mounted on the engine plates. The buffers bolt to the frame, allowing the powertrain to vibrate without transmitting its shuddering to the rider. Lateral movement is controlled by shims — it’s said this was Poore’s contribution. A notorious cheapskate, he apparently nixed screw adjusters in favor of cheaper shims, which required awkward and time-consuming fettling by the owner. Vernier adjusters did appear, but not until the last MkIII Commando in 1975.
At the time, cynics sneered that only a British manufacturer would take a bike with an obsolete engine (the Atlas), and a great frame (the legendary Featherbed), then ditch the frame and keep the engine! Nevertheless, the Commando was a critical and commercial success. It went on to win Motorcycle of the Year in British rider polls five years in a row, while staving off the collapse of the British motorcycle industry.
Tony Duffett, R model: “I like the older style touches, like the twin leading shoe brake,” Tony says. “The early models — like the R — also came with a narrower front tire, so they’re a little quicker handling.” Tony has also heard from various sources that the R came with a different profile camshaft. “This one is a really strong motor. It makes great power,” he says, especially compared with the 1971 Roadster he also owns. “I also prefer the sound that you get from the earlier style Dominator exhausts. They’ve got a deeper, throatier sound. Overall? “It’s a great around town motorcycle.”
Jim Bush, S model: “The R was the initial step at ‘consumerizing’ the Commando,” Jim says. “The S took it all the way with the naked front, high-level exhaust pipes and peashooter mufflers.” Jim’s S retains the stock 19-tooth countershaft sprocket and direct-drive rear hub — early Commandos have no driveline shock absorber. “Great for quick starts,” Jim says, “but tough on chains and sprockets. “There’s an incredible feeling of instant power and performance, and it’s different from anything else you’ll see,” Jim says. “It’s a Sixties hooligan in a sequined suit!”
Dave Guthrie, SS model: “I always wanted a high-pipe Norton,” Dave says, who now owns two. The SS had just 4,300 miles when Dave bought it, and it’s still running stock pistons. One curiosity, though: it came fitted with a later Combat cylinder head. “It rides like a dream,” he says. “It’s very fast, but you’ve got the wide scrambler bars, so you’re out in the wind.” Dave also notes that the seat is an inch or more higher than the Fastback. Longer rear shocks? “I think it’s just the seat itself,” Dave says. He also owns a Roadster model, but finds the SS more direct feeling. “It’s so tight,” he adds.
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