1973 John Player Norton Monocoque
A classic Norton racer
July/August 2010
By Alan Cathcart
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The 1973 John Player Norton Monocoque.
Photo by Kyoichi Nakamura
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1973 John Player Norton Monocoque
Engine: 746cc air-cooled OHV parallel twin, 73mm x 89mm bore and stroke, 10.5:1 compression ratio, 76hp @ 7,200rpm
Top speed: 158mph
Carburetion: Two 33mm Amal Concentric 932
Transmission: 5-speed Quaife, chain final drive
Electrics: 12v, Lucas Rita electronic ignition
Frame/wheelbase: Stainless steel monocoque/56in (1,422mm)
Suspension: Leading-axle Norton-AJS telescopic forks front, dual Koni/Girling shocks with adjustable preload rear
Brakes: Dual 10in (254mm) discs front, single 8.5in (216mm) disc rear
Tires: 3.5/3.25 x 18in Dunlop KR124 front, 3.75/5.00 x 18in Dunlop KR124 rear
Weight (dry): 350lb (150kg)
Weight distribution: 48/52 front-rear
Fuel capacity: 6.35gal (24ltr)
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Although only three John Player Norton monocoques were ever built (plus a fourth prototype chassis), all of which competed for just a single race season in 1973, its unlikely success against much more powerful 2-stroke opposition cemented the JPN as a benchmark motorcycle racer of the modern era.
The John Player Norton story is much more than a footnote in the history of Britain’s oldest and most historic marque, denoting a brief revival of race track fortunes in the face of a burgeoning Japanese onslaught. Thirty-eight years ago, Norton’s tiny race shop not only established the prototype of the modern fully sponsored road racing team, it also created a winning motorcycle racer bike that, while essentially a 2-wheeled anachronism thanks to its archaic air-cooled pushrod 2-cylinder engine and separate gearbox, was arguably the most sophisticated and avant-garde motorcycle in terms of chassis design that the world had yet seen.