This bike is using a concept prototype engine I built in 1983, for the Ultralight Pioneering Project with Steve Cohen. Initially I used a 350cc single cylinder. .. (see Archives : Ultralight)
A propeller can only go a certain speed. I came up with the Flat twin, rotary valve head to carry the prop. The rotor running 1/2 engine speed to slow the tip speed of the prop down. The prop was mounted to the rotary valve.
This engine was never finished at that time. 35 years later it is still with me… after all this time it has been put together now as a Speedway concept/bespoke piece of Art.
665 cc opposed flat twin. Both cylinders are at top dead center at the same time, and both are mounted to the rotary valve head that fires every 360 degrees.
Both crankshafts are connected to the rotary valve by chain drive.
The single central rotor travelling at 1/2 engine speed services both cylinders.
The actual rotor is 70mm in diameter and runs on 2 large ball racer bearings in the cylinder head. Off the end of the rotor where the prop would have originally been mounted is a chain drive connecting to a jack shaft in the frame. The other end of the jack shaft drives the rear wheel.
The rotor has an inlet and exhaust port: exhaust port comes out the drive side & inlet comes in through the top. The rotor fires that particular cylinder then rotates around at 1/2 engine speed.
Crankcases machined out of a solid block. The crank shaft protrudes through one side of the case.
Fuel Tank is a double acting Windmill pump
Manufactured top and bottom yolks to suit the BSA 1930’s Girder Forks
Manufactured sand bent frame.
2 x 23” Front rims from Honda XL500
International Harvester Co. 4 cylinder Magneto
S.U Carburetor from 1950’s
German throttle lever SUD JLO WERK