ManufacturerArielYear1960Engine Size700ccAbout the Ariel Leader 4 This fascinating 700cc prototype, tested at Ariel circa 1960, shows that BMWs four-cylinder K100 was not exactly original when unveiled in 1983.
The prophetic Ariel looks similar to the companys innovative 250cc Leader two-stroke launched in 1958, with a pressed-steel frame, leg shields and windscreen. But the power unit is unlike anything else from a British factory. The crankshaft is set in-line with the frame and slightly offset to the right, with four horizontal cylinders on the left. Final drive is by shaft, via a four-speed gearbox is built in unit with the engine. Cooling of the exhaust port area is fan-assisted and oil is carried in a wet sump.
Found to be comfortable, tractable and extremely quiet, the luxury electric-start Leader 4 was not fast. In prototype form, the single carburettor engine designed by industry veteran Val Page produced no more than 25bhp. Ariel engineers believed their design had potential, but the parent BSA Group saw no future for it in the age of the BMC Mini car and cancelled the project.
Steve..
Cracked it, well you live and learn. Never came across this one before, however it is not an in line across the frame, as was the norm, like Honda, MV Agusta, Gilera etc. the engine runs along the frame, like car engine. Even then, you will notice on the picture of the bike, that the side panels are not there. This engine was 700cc God knows how they stopped the bike, if they used the standard "leader" drum brakes (no Discs on bikes then) Very interesting, Steve, Glad you bought it up. Guess we had better get back on the original thread, about the BSA. Malc.