There are no works records for any bikes produced in the first year , either there were never any records made or they have subsequently been lost
Production was the MK 1 OHV. Without records production numbers are unknown. One complete bike survives and a few engine parts
The general design of the frame and cycle parts was similar to that of other makers, with the exception of the Brough Superior trademark to be, a Saddle tank that was all curves and sparkling nickel plate. The standard of finish was also a cut above the average. This was George Broughs first dream bike, not the flat twins that his father was producing. In the first adverts he referred to it an ‘Atmosphere Disturber’.
The engine of the MK 1 is known as the ’90 bore’, a 50 degree V twin with 90mm bore and 75mm stroke. The valves are set vertically, the valve guides are in detachable port blocks with valve seats in the cylinder barrel top), the valves are removed by unscrewing the valve guides. Not an easy engine to work on.
The performance was not sparkling, 80mph was the best one could hope for. In 1920 this was still a speed that could turn heads.
Stopping would also be poor, with the first fitted with the archaic stirrup push bike style front brake and a dummy belt rim rear brake. Sometime referred to these brakes as “ paint scrapers”, because all they were good for was to remove paint from the wheel rim.
Gearbox was Sturmey Archer CS 3 speed, in common with most of the rest of the motorcycle industry.
Open diamond frame with Enfield or Webb wheels and Brampton no 2 or Brampton Biflex front forks.
Headlamp typically a Lucas acetylene one, a tail lamp was not a specific requirement until 1930.
There are no hard and fast ‘rules’ for what was fitted in the early years of production, decisions were probably arrived at depending on what was available within the industry at that time in the yearand what George could get by doing a best price deal.
The last is borne out by recent research into the dating of the 90 Bore engines. It would seem that they were at least 6 or so years old when GB purchased them. He probably offered to take them of Messrs JAP hands for a job lot price.