MOTOBÉCANE

500 BS Four-Cylinder - 1929

Motobécane had only been in business for four years in 1929, but it had big ambitions. Initially, the company's development had followed a sensible, logical progression. But then one of its founders, Charles Benoit, responsible for product planning, fondly recalled being posted to the US as an officer-instructor during WWI.

Dream Bike

He had been impressed by the newly-launched Cleveland and Henderson fours and had been inspired to create a similar dream bike on a French scale.

Clean Modernity

The design staff admirably executed the boss's ideas. This new unit-constructed four was clean and modern, with its cylinder block cast in aluminum with an iron liner. The crankcase had no central joint, and the two-bearing crankshaft was inserted through the rear of the casing. The balanced connecting rods were proved with pressure lubrication, while a vertical shaft at the forward end of the crankcase drove the distributor for the coil ignition and the oil pump. The gearbox–built in unit with the engine, alongside the

rear two cylinders – was driven by gearing, False hopes with a clutch between the output and the transmission, as on the Honda CX and GL. In contrast with the chain-driven US four-cylinder bikes, the crankshaft and gearbox turned counter-clockwise, which eliminated the out-of-balance forces common to inline engines. This first four-cylinder Motobécane was praised by the press, but its shortcomings soon became apparent. It was slower than the 500 single, refused to turn faster than 4500 rpm and overheated horribly. The project was quickly abandoned in favor of an ohc 750.

SPECIFICATIONS

Engine: 477cc (45x75mm) air-cooled four-cylinder four-stroke

Valves: side

Fuel System: 18mm Amac carburetor

Transmission: 3-speed, hand-shift, shaft-and-bevel final drive

Suspension: girder forks (front); rigid (rear)

Brakes: drum (front & rear)

Wheels: 3.50x19 inch (front & rear)

Weight: 265 lb

Only ten of these four-cylinder models were built, under the designations "B5" (Motobécane) or "T5" (Motoconfort); two are known to survive.