Four stroke, single cylinder, DOHC, fully enclosed rockerbox
Capacity
498.3 cc / 30.4 in
Bore x Stroke
86.1 x 85.6 mm
Cooling System
Air cooled
Exhaust
Single
Induction
AMAL Concenrtic 932 R300
Ignition
Lucas magdyno, 6V
Starting
Kick
Max Power
38 kW / 51 hp @ 7200 rpm
Transmission
4-Speed, AMC
Final Drive
Chain
Frame
Norton Featherbed, double cradle
Front Suspension
Ceriani telescopic fork
Rear Suspension
Swingarm, twin shocks
Front Brakes
Drum, 4 leading shoe
Rear Brakes
Drum, single leading shoe
Wheels
Akront
Front Rim
19" rim
Rear Rim
19" rim
Front Tyre
Avon Roadrunner 90/90 19 52H
Rear Tyre
Avon roadrunner 19
Top Speed
225 km/h / 140 mph
.
Norton Manx Story
The Norton company has always applied the term "Manx" to the
racing motorcycles that it produces in limited quantity for the open market. The
name refers to the Isle of Man, where the Tourist Trophy is run. This annual
race attracts the finest British racers, who compete on racing motorcycles that
have been derived from production models are are available on the open market.
Norton built its first Manx (although it was called an International at the
time) in 1932. Derived from the Grand Prix, the motorcycle was the work of
Arthur Carrol and Joe Craig. The tuning and modification of the Internationals
was left to the customers, who proved to be up to the job.
Meanwhile the racing department of the company continued to
modernize the official models, which were transformed rapidly in those years to
meet the tough competition provided by the motorcycles and racers of Rudge,
Velocette, and Sunbeam in Britain, and Bianchi, Guzzi, and Moto-sacoche on the
Continent.
Between 1936 and 1938 the bore and stroke of the Grand Prix 500 were changed
twice and a double overhead camshaft distribution was installed for the first
time. Before racing was halted by World War II, the official Norton 500 boasted
a power of 50 h.p. No other single-cylinder engine of that class could generate
more horsepower, but its power was not enough to discourage the Italian and
German makers of multi-cylinder models. Norton managed to hold its own,
especially on mixed circuits, where its weight-power ratio helped racers.
The Norton company was fortunate to have such fine racers as
Jimmy Guthrie and Harold Daniell, two of the greatest champions of the time, and
new racers were continually appearing on the scene.
The first Norton motorcycles to reappear in racing in 1946
were old models that had been jealously guarded by their owners. Throughout
Europe most of the racers who won improvised races had old SOHC Nortons,
and the official Norton team reappeared with prewar DOHC motorcycles.
Indeed, with the prohibition of superchargers it almost looked as if the
single-cylinder might rule the roost, or at least have a temporary advantage
over the four-cylinder Gilera, the two-cylinder BMW, and the two-stroke DKW. In
reality, after losing the 1949 world championship to the two-cylinder AJS
Porcupine in the 500 class and to the single-cylinder Velocette in the 350
class, Norton had to struggle in the following years to defend the slight margin
that its racers had succeeded in winning for it.
From 1951 on, the chief factor in Norton wins was its
innovative Featherbed chassis, which was designed for Norton by the McCandless
brothers. With this chassis Norton could outrace any motorcycle of equal power,
especially on difficult tracks.
The Norton Grand Prix won the world championship in 1950 (500
class), 1951 (350 and 500), and 1952 (350). These were not easy wins, and much
credit was due to the fantastic skill of Geoffrey Duke, for whom the
single-cylinder was perfectly suited.
In 1949 the Norton International had become the Manx. That was the year the old
SOHC system was replaced by a DOHC one. In 1952 the
Manx was given a squared-off engine.
In 1954, after Italian multi-cylinder motorcycles had outraced
the Norton (despite the valiant efforts of Ray Amm), the company decided that as
of 1955 only Manx models would be entered in races. Beginning in 1955 private
racers throughout the world also defended Norton's colors with honor.
Tuned by specialists, the final version of the Norton Manx 500 was considerably
more powerful than the Grand Prix model from which it had been derived. And for
some time to come it was a real threat to the most advanced motorcycles that
entered the Tourist Trophy.
Any corrections or more information on these motorcycles will be kindly appreciated.