Four stroke, parallel twin cylinder, push rod
2 valves per cylinder.
Capacity
829 cc / 50.6 cu in
Bore x Stroke
77 x 89 mm
Compression Ratio
8.5:1
Cooling System
Air cooled
Induction
2 x Ø32 mm Amal concentric carburetors
Ignition
120W Lucas alternator
Starting
Electric and kick
Max Power
60 hp / 44.7 kW @ 6200 rpm
Clutch
Metal diaphragm clutch
Transmission
4 Speed
Final
Drive
Chain
Frame
Twin downtube cradle with Isolastic engine mounts
Front Suspension
Telescopic forks
Rear Suspension
Swing arm with Girling coil springs
Front Brakes
Single disc
Rear Brakes
Single disc
Front Tyre
4.10-19
Rear Tyre
4.10-19
Wet Weight
233 kg / 514 lbs
Fuel Capacity
19 Litres / 5.0 US gal
Average Fuel Consumption
5.3 L/100 km / 18.7 kn/l / 44 US
mpg
Standing ¼ Mile
14.4 sec / 145 km/h / 90 mph
Top Speed
185 km/h / 115 mph
The parallel-twin four-stroke engine is an integral part of British motor
cycling history, and in recent years the two mainstays of the British industry
relied on this layout, the particular machines concerned being the Triumph
Bonneville and Norton Commando.
Although basically similar, the engines of the two bikes differed somewhat in
character with the Norton engine seeming a lot more powerful and 'gutsy' low
down. Very much an undersquare engine, it was not surprising that torque was its
strongpoint and that the engine became rather breathless above 6000 rpm. As
might be expected, the simple and reliable pushrod-and-rocker valve system was
used, along with a mild 8.5: 1 compression ratio. The Commando was not short of
power, however, and developed 58 bhp at 5900 rpm from its 828cc, enough to give
it a very respectable performance. Breathing through two 32 mm Amal
carburettors, it could also be very economical, with fuel consumption reaching
anything up to 60mpg.
The engine was coupled to a four-speed gearbox which, even with the ample
power available, still had one ratio too few. The gearchanges and clutch action were remarkably
light, and made for quick and fuss-free cog swapping. The Commando Isolastic
frame was a tall and narrow duplex design, featuring rubber mountings for the
engine which helped to insulate vibrations above 3000 rpm. Not surprisingly with
its racing heritage, the big Norton was very much at home on twisty roads, with
its well designed steering no doubt helping to make it handle neutrally and
safely in any situation.
The last Mk III Commandos were somewhat softer than their predecessors, with
inferior performance. The top speed of the Mk III was, however, a creditable
110mph with a standing-start quarter-mile time of just over 14 seconds. The
average fuel consumption was 45mpg, and consumption did not drop much below that
figure even if the bike was ridden hard.
It was obvious in later years of its life that the Norton company was
pandering to the tastes and demands of the American market with the bike. This
was emphasized by the machine's electric start system. For many years, Norton
enthusiasts ! developed strong right legs for starting their machines, but the
mid-1970s American market dictated that a push-button system would not only be
acceptable but essential for their large share of the Norton production. So,
such a system was fitted, the only problem being that it was hardly powerful
enough to get two 360 degree, 424cc cylinders into action. The Americans were
happy, for the bike displayed the legend 'Electric Start' on the flanks and the
dealers took it seriously; weaker riders could always use the button in
conjunction with the kick starter so things were not too bad.
Once under way, the Commando was a .superb riders' machine, for it cornered
very swiftly and stopped equally quickly in wet or dry, the single Lockheed
discs front and rear making light work of hauling the 430 lb bike down from high
speeds.
Although in its Mk III guise the Commando was not as quick as its
predecessors, it was still a well-loved and capable machine. NVT, however,
decided to concentrate on the more modern, three-cylinder, Triumph Trident and
so the Commando was quietly dropped. Not long after that the triple itself went
out of production but the Norton name was left for the Wankel-engined bike upon
which so many hopes for the future of the British bike industry rested.