1973 Norton Commando
1973 Norton Commando Background & History
The 1973 Norton Commando came after the dismal finish of the 1972 model year which, thanks to the Combat engine, cost Norton tons of money, time, energy, focus and worst of all, reputation. 1973 was a good year for Norton Motorcycles. The entire model line had benefited from the engine fixes developed to counter the Combat’s tendency to break pistons and eat main bearings. The new Superblend main bearings were now standard on all models. While the Combat engine continued to appear in the catalog briefly, it had been canceled in 1972 because the problems were just too great and Norton’s scarce resources needed to be directed into its mainstream line of engines. Norton also hoped to benefit by the demise of BSA in 1972. But Triumph was still hanging on and and 1973 was a big year for them with the Bonneville growing from 650 to 750cc, and finally gaining a 5-speed and front disc brake. This was the British motorcycle industry’s (what was left of it) last big push. It lasted about two years.
The 1973 Norton Commando Roadster had now grown to an 850, although it was still available as a standard 750 or a Short-Stroke 750. The front disc brake was standard, but still no 5-speed.
1973 Norton Commando Model Designation
When the 1973 Norton Commando lineup was announced, the Commando Fastback and Fastback LR (Long Range)had been dropped. The 1973 Norton Commando Roadster, Interstate and Hi-Rider continued on in MkV form, now with optional turn signals, which had only been listed for the first time as an option on the 1972 Norton Commando Interstate. All engines now had the 32mm Amal 932 Concentric carbs and intake tracts from the Combat engine, but with reduced compression ratio & higher gearing. Only the Hi-Rider soldiered on with the old 8-inch TLS front brake, all others now had a single front disk brake on the right and the old drum out back.
The 1973 Norton 850 Commando Fastback was a cosmetic package with a stock Commando underneath. The tank, seat, rear fender cover and side covers were unique to the Fastback, and rubber fork gaitors were added.
1973 Norton Commando is the First 850 Commando
The biggest news for the 1973 Norton Commando was the new 850 Commando line. Yes, the ancient 1948 Bert Hopwood design that started life as a 500cc, then to 600, then 750, then 750, had one final growth spurt, this time to 829cc, to be called the 850 Commando. This was accomplished by boring the cylinders out to 77mm and retaining the 89mm stroke. The compression ratio was lowered to 8.5:1. Power output was advertised as 60hp at a leisurely 6,200rpm, but was probably more like 53hp, pretty much the same as the 750. The difference was that the 850 got it done with much less stress, at a lower rpm and was thus smoother and more reliable. Prolonged cruising at 5800 rpm was possible and this calculated out to about 100mph in top gear. A redesigned cylinder block now had through bolts from head to crankcase as well as short studs and nuts. Flywheel weight was adjusted to compensate for the heavier pistons. An all-metal clutch and reinforced gearbox casing were added. A cross-over pipe now joined the two exhaust pipes just downstream from the heads.
The 1973 Norton Commando Model S was looking more like a dirt bike every year. However, the front fender was now mounted to the fork slider instead of fixed to the lower triple clamp as in 1972, and a new small tank was specified. The front brake is a conical drum brake unit unique to the Model S.
1973 Norton Commando is Both a 750 & 850
The 750 and 850 were both produced throughout most of 1973 and were available in all models. In October 1973, the last 750 rolled off the assembly line. Well, that’s not exactly correct. Because a new short-stroke 750 was briefly offered as an option on the John Player Norton and the Commando Roadster. By shortening the stroke to 80.4mm while retaining the 77mm bore from the 850, the new displacement was 749cc (the old 750 was actually 745cc), with a less undersquare engine geometry. It's almost comical that the 'Short-Stroke' 750 had a bore & stroke of 77mm X 80.4 mm, not exactly what many would call 'short'. Mechanically, longer strokes relative to the bore generally tend to make less power but more torque at lower RPMs, where as shorter strokes make more horsepower but at higher RPMs. The goal of the Short Stroke 750 was to rev higher and make more power than the standard Commando 750. The Short Stroke engine was an offshoot from the works experience Norton gained in production racing.
This 1973 Norton Commando Interstate has the lower UK-spec handlebars, but otherwise is like the US versions, with the large 5-US gallon tank and higher gearing.
Trouble in Paradise
By 1973, Norton Motorcycles looked like the strongest, most viable of the British Motorcycle Manufacturers. Once mighty BSA and Triumph had sustained huge losses and suffered from horrendous management, BSA closed it's doors in 1971, leaving orphaned Triumph on the verge of collapse. In July 1973, Norton’s parent-company, Manganese Bronze Holdings, with help from Britain’s Department of Trade & Industry, bought the beleaguered BSA and Triumph brands and formed a new company called “Norton Villiers Triumph”, or NVT. With it came a new plan: Close Triumph’s legendary Meriden factory and move all Triumph production into Norton’s Wolverhampton plant. When the Triumph workers got wind of this, they immediately took over the Meriden facility and shut it down for the next 18 months, halting all Triumph twin production throughout most of 1974. Norton's plans to make Triumph profitable were dashed. Norton's problems were many, and were emblematic of the British motorcycle industry as a whole, and were quickly compounding and growing out of control.
The 1973 Norton Commando Hi-Rider thundered into another year. Hard to believe it hung on this long.
The venerable old Norton twin, launched in 1949 as a 500, was quickly expanded to 600, then 650, the 750cc, and now in 1973 it got pushed out again to 828cc, to be called the 850 Commando.
1973 Norton Commando Specifications
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Model designations: Engine type Displacement 750 Displacement 850 Displacement, Short-Stroke 750 Bore & Stroke 750 Bore & Stroke 850 Bore & Stroke Short-Stroke 750 Compression Carburetors Ignition Engine output Oil system Oil capacity Primary drive Clutch Gearbox Ratios, overall: 1st, bottom 2nd 3rd 4th, top Final drive Frame type Suspension, front Suspension, rear Brake, front Brake, rear Wheelbase Seat height Weight |
Fastback Interstate Roadster Hi-Rider Model S Air-cooled OHV parallel twin 746cc / 45 ci 828cc 749cc 73mm X 89mm / 2.875″ X 3.503″ 77mm X 89mm / 3.03″ X 3.503″ 77mm X 80.4mm / 3.03″ X 3.17″ 8.5:1 2- Amal Concentric, 32mm Battery & coil, Lucas 60 bhp @ 6200 rpm Dry sump 6 pts Triplex chain Multi-plate diaphragm, wet 4-speed constant-mesh, right-foot shift 12.40:1 8.25:1 5.90:1 4.84:1 Chain Double cradle, Isolastic Suspension Telescopic fork, hydraulic damping Swing Arm, 2 dampers, Isolastic mounts 10″ disk, 2-piston hydraulic caliper 7″ SLS drum, full width 57.1″ 31.3″ 430 lbs |
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