Photo ou archives : F-M. Dumas
7319
350 R4C - 1935
Own-make engine
An important year for the twin marques from Pantin (Paris), Motobécane and Motoconfort, was 1930. After having fitted four-stroke Blackburne engines, they decided to free themselves of their dependence on a British supplier.
Unit Construction
Showing a certain technical awareness, they opted for a unit-constructed engine rather than for the traditional separate engine and gearbox layout. This was the Motobécane "B" unit (coded "T" for Motoconfort), built in 250,350 and 500cc side- and overhead-valve capacities. They were joined the following year by a 175cc side-valve engine. The 500 B5C "Grand Sport," with dual exhaust pipes and a four-valve head, was top of the range. There were also two four-cylinder models, the 500cc B5 and 750cc B7.
Wider Range
At the 1933 Paris Salon, the "B" engines were joined by the "S" units ("M" for Motoconfort), an improved design – particularly in regard to lubrication, which used a constant-level system with an oil tank and float incorporated in the power unit. This engine powered the side-valve 350cc R4 and overhead-valve R4C in 1934. The "S" engine was also available in 250 and 500cc side- and overhead-valve form as well as a four-valve version on the R4C "Grand Sport." As for the gearbox, it had just three speeds, with either a shift lever on the tank or a foot-selector at the front of the unit. In 1935, the power unit was also available with four speeds. Its career ended in 1948, with the famed 350 R46C "Superculasse."
SPECIFICATIONS
Engine: 350cc (70x90mm) air-cooled single-cylinder four-stroke; constant-level lubrication; magneto ignition
Valves: overhead
Fuel System: carburetor
Transmission: 3-speed, hand- or foot-shift; chain final drive
Suspension: girder forks (front); rigid (rear)
Brakes: drum (front & rear)
Wheels: 26x3.50 inch (front & rear)
Weight: 265 lb
Maximum Speed: 59 mph
The R4C was a good-looking bike, with its cleanly-designed unit-constructed engine and "tongues of flame" paint job.