Norton Classic
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| Manufacturer | Norton Motorcycle Company |
|---|---|
| Also called | P43 |
| Production | 1987 |
| Engine | 588 cc (35.9 cu in) air-cooled twin-rotor Wankel engine |
| Transmission | duplex primary chain, 5-ratio gearbox, single-row final drive chain |
| Wheelbase | 1,486 mm (58.5 in) |
| Related | Norton Interpol 2, Norton F1, Norton Commander |
The Norton Classic is a rotary-engined motorcycle built in 1987 by Norton as a special edition of just 100 machines.
Contents
Engine development
The Classic used an air-cooled twin-rotor Wankel engine that had been developed by David Garside at BSA's Umberslade Hall research facility.[1][2][3]Garside, who had been impressed by the air-cooled single-rotor Fichtel & Sachs engine in the Hercules motorcycle, installed a bought-in F&S engine into a BSA B25 'Starfire' frame as a "proof of concept". This proved reliable and smooth, but under-powered. Garside then created a prototype twin-rotor engine (with F&S rotors) which doubled the capacity of the earlier test "mule". This twin-rotor engine was installed in a BSA A65 frame.[4]
Wankel engines run very hot, so Garside gave this air-cooled motor additional interior air-cooling. Air was drawn through a forward-facing filter situated to provide a ram air effect. This air passed through the interior of the rotors and then into a large pressed-steel plenum before entering the combustion chambers via twin carburettors.[5] The plenum (which doubled as the bike's semi-monocoque frame) enabled the transfer of much of the heat to the surrounding atmosphere. The carburation process further reduced temperatures via the heat of evaporation. Even so, at 50°C the fuel-air mixture was still hotter than ideal, and the engine's volumetric efficiency remained somewhat impaired The eccentric shaft's main bearings and the inlet manifolds were fed by oil-injection lubrication, and the fuel-air mix also carried residual mist of oil from the interior of the rotors, which helped to lubricate the rotor tips.[6]
The Classic motorcycle
While its engine was revolutionary, in other respects, such as appearance, suspension and brakes, the Norton Classic was a conventional twin-shock roadster. The fork stanchions were protected by rubber gaiters; and a full enclosure protected the final-drive chain. The air-cooled Classic was lighter and more powerful than its only Wankel competitor in production, the over-complicated single-rotor Suzuki RE-5 motorcycle (which had liquid-cooled jackets and an oil-cooled rotor).
The Classic was discontinued after a limited production run of only 100 motorcycles,[7] and was succeeded by the liquid-cooled Norton Commander. Liquid cooling provided both greater reliability and greater power, at the expense of an arguably less attracive engine (which was concealed by a full fairing).
Wankel engines in motorcycles
Compared to piston engines, rotary engines are smooth, light, compact, and produce high power outputs from relatively small displacements. Although these attributes are so beneficial to motorcycles that the rotary engine was heralded as the future of motorcycling, nevertheless Wankel-engined bikes remain something of a rarity.
One reason for the scarcity of Wankel motorcycles is that both manufacturers and customers are much more familiar with piston engines. Compared to pistons, the rotors of a Wankel engine are massive and need time to warm up; yet, as NSU found to their cost with their Ro80 car, neither bikers nor drivers have been patient enough to give the engines time to reach operation temperature, and this impatience adversely affected reliability. By contrast, the benefits of being smooth, light, compact, and powerful makes the Wankel ideal for light aircraft, where the process of preliminary checks and taxiing gives ample time for warm-up before full take-off power is required.
As an example, the Norton Classic's Wankel engine was further developed at Staverton into the MidWest aero-engine. The Midwest engine's output increased from BSA's 85 bhp to nearly 110 bhp by improving volumetric efficiency as follows: cooling air was pumped under pressure by a belt-driven centrifugal fan through the interior of the rotors, but then dumped overboard. Filtered induction air at ambient pressure was then drawn into the combustion chambers.[8]
References
- ↑ The Wankel Rotary Engine: A History By John B. Hege page 137, ISBN 978-0-7864-2905-9
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ "BSA, Born 1861, died 1973" - W P Murray, July 1994 - Staffordshire
- ↑ "Bike" magazine Summer 1973
- ↑ "Cycle World" magazine February 1971
- ↑ Bill Murray monograph 1985: "The decline of the British motorcycle industry"
- ↑ Salvadori, Clement. "Retrospective: Norton Classic, 588cc Rotary Engine: 1988" Rider Magazine, 22 November 2007. Retrieved: 2 August 2012.
- ↑ MidWest Engines Ltd AE1100R RotaryEngine Manual
Bibliography
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