Norton Dunstall

 

 

 

Make Model.

Norton Dunstall

Year

1966 - 75

Engine

Parallel twin, OHV

Capacity

745 cc / 45.5 cu in
Cooling System Ari cooled
Starting Kick

Transmission 

4-Speed
Final Drive Chain
Wheelbase 1410 mm / 55.5 in
Seat Height 800 mm / 31.5 in
Source Wikipedia

Paul Dunstall was a specialist tuner of Norton twins in the 1960s and early 1970s. He started modifying Nortons in 1957, at the age of 18, when he converted a Norton Dominator into a competitive racing motorcycle. As well as fitting a Norton Manx gearbox and wheels, Dunstall balanced the crankshaft and installed the Dominator engine into a Manx Norton frame. With places and two outright wins at Brands Hatch in his first season, after graduating to a higher level with places in his second season at other circuits, Dunstall retired from racing to work in his family's scooter shop and develop performance motorcycle parts

Initially Dunstall conceived simple 'bolt on' modifications such as 'Goldie' pattern straight-through replacement silencers which he called 'Hi-Tune' and exhaust pipes, creating his first catalogue in 1961 and gradually growing the business.

Dunstall built engines for other racers and purchased parts left over from Norton's Domiracer project when the factory closed in 1963, using his know-how to further develop high performance motorcycles built to order.

From 1966, Dunstall's customers could choose from a standard catalogue offering a range of speed parts, race-styled accessories and complete ready-modified bikes[4] from Norton, BSA, and Triumph in capacities from 500cc upwards.

In 1966 Dunstall Motorcycles became a motorcycle manufacturer in its own right, so that Dunstalls could compete in production races and the Auto-Cycle Union, which is the governing body for motorcycle racing in Britain, approved Dunstall Dominators as a marque for the production race in the 1967 Isle of Man TT.

The last bikes from the featherbed-based machines in the 1969 catalogue were stated as Dunstall Norton Sprint and Export 750 together with the newest bike in the range the isolastic-framed Dunstall Norton Commando.

By the late 1960s, Dunstall had sold to celebrity customers including film star Steve McQueen and Keith Emerson, of progressive rock band Emerson Lake & Palmer.

After the 1968 race season successes, development of the late-1940s designed parallel twin engine was nearing its zenith for the technology of the time with power outputs of 73 horsepower for the race-spec 745cc Atlas-based engine.

For the 1969 season, Dunstall created a new machine with a lower frontal area, the inclined engine being 'underslung' from a large-diameter steel tubing spine frame (nicknamed The Drainpipe) designed by Eddie Robinson The main frame component ran front to back with a second large-diameter vertical tube at rear of the power plant carrying the engine oil, avoiding the need for the traditional separate oil tank. The filler was conventionally placed ahead of the seat nose.

Although Dunstall's open-class racers (non production-race category) were equipped with lowboy frames based on the works design which Dunstall had acquired during the Norton factory race-shop closure, this re-design was based on an established concept not yet applied to the Norton twin for road racing. With no front downtube(s) hence no conventional engine mountings, the spine frame needed substantial cantilever bracing from the central-point of the frame forwards under the gearbox and engine to control the torque reaction

The original 'drainpipe' configuration included aluminium dual 'pannier' fuel tanks inside the top-half fairing sides to lower the centre of gravity and improve handling but following fuel starvation problems a conventional fuel tank was fitted.