1962 Norton Petty-Molnar 519cc Manx Road Racing Motorcycle, Frame no. PETTY PR93006 Engine no. MOLNAR 066

1962 Norton Petty-Molnar 519cc Manx Road Racing Motorcycle
Frame no. PETTY PR93006
Engine no. MOLNAR 066
• Owned by former AHRMA National Champion John Cooper
• Molnar short-stroke motor rebuilt by the late Bob Barker

This distinctive machine represents the final evolution of the Manx Norton as developed by noted English tuner Ray Petty. He spent a lifetime extracting winning performances from the big bangers – including five British championships from 1962 to 1966 with Derek Minter. In 1971 Petty prepared the last single to win a British championship and continued to tune Nortons for classic racing until his death in 1987, recording more wins than the famous Francis Beart in whose shop he had served an apprenticeship. In 1971 Petty started making his own race frames, which were lower and quicker-handling, adopting Colin Seeley's swingarm design – rear axle securely clamped to sliding blocks of aluminum – with added triangulation to the steering head. He bronze-welded the frame using thin-wall T45 carbon-manganese steel alloy aerospace tubing. White Rose Racing went on to build 'continuation' Petty-style frames following his death. "Taut and predictable like a wideline Featherbed combined with lightness and ride comfort," said Classic Racer magazine of the design in 1992.
This particular Petty-framed Manx was developed further to meet AHRMA rules. Its Molnar short-stroke engine (92 x 78mm) displaces 519cc, the maximum AHRMA overbore, and uses a lightweight crankshaft assembly with needle-roller big end, a Carrillo rod and a JE forged piston. Titanium valves are attended by R/D springs that are fully enclosed, eliminating that source of oil leaks. The motor was built by the late Bob Barker, a former Can-Am development engineer who went on to become a most reputable Manx engine expert. Inhaling via a 1½in. Amal GP carburetor and sparked by an electronic PVL magneto built by Brian Richards, there's a strong 60bhp at the crank (an engine-tuning file comes with the bike). The clutch is from NEB and is mated to a six-speed TT Industries magnesium-casing gearbox. Magnesium brakes – a Fontana 210mm up front and Norton conical at back with a floating backing plate mount – mean the Norton is not lacking for binders. Suspension is of equal quality: Computrak-tuned Roadholder forks and ultra-light Works Performance shocks. So this fire-breathing, nimble-handling Manx is guaranteed to go as good as it stops as good as it steers!
The alloy gas tank is a Manx short-circuit style, mounted in front of a custom, hand-formed alloy seat and tailsection. The whole bike is freshly painted in black and silver, and all alloy surfaces have been polished. This well-sorted Manx has competed at many racetracks in North America, ridden by Hourglass Racing's Chuck Davis and by Team Whitworth's John Cooper, the machine's current owner. Cooper was AHRMA Classic 60s National Champion in 2000 on a BSA Gold Star. Today, the Norton is beautiful, race prepared and track ready. Choose practice days, AHRMA 500 Premier competition, or just display – this Petty Manx will succeed at any one, or all three!