Photo ou archives : F-M. Dumas
3515
MOTOBÉCANE
500 R46C "Super-culasse" - 1948
Saga of the "superhead"
The second major French constructor to adopt the unit-construction engine after Peugeot, Motobécane remained absolutely faithful to this technique on every one of its four-strokes from 1930 through 1960. Not every one was a show-stopper, but the different versions of the "Super-culasse" (super cylinder head) model became famous.
Born to Race
The first successes of the unit-construction Type "B" single, launched in 1930, came in 1932 with Lovinfosse's win in the Bol d'Or endurance race on a four-valve 500. In turn, the four-speed Type "S," introduced in 1934, won the sidecar class of the Bol d'Or in 1935 and the 250 solo category in 1937.
Enter the "Super-Culasse"
In 1938, works-backed privateers entered the Bol d'Or riding Type "S" machines whose special aluminum and bronze cylinder heads had totally enclosed valve gear. They dominated the sidecar class, coming first and second in the 350 and first in the 600. The same year, this "Super-culasse" became optional on the 500 SSC Grand Sport. In 1939, it was standardized on all production 350 and 500cc ohv models. In the Bol d'Or "Super- culasse," Motobécanes set a new distance record of 1212 miles, won both 350 sidecar and solo classes and came second in the 500 solo category. This run of success was brought to an end by the war. However, the tools used to produce the 350 "Super-culasse" survived the war, so in 1948 Motobécane launched the R46C with the 1939 power unit in a new frame with telescopic front forks and plunger rear suspension.
SPECIFICATIONS
Engine: 493cc (80x98mm) air-cooled single-cylinder four-stroke; Novi magdyno ignition
Valves: overhead; twin port head
Fuel System: carburetor
Transmission: 4-speed foot shift; multi-disc steel/bronze oil-bath clutch; chain final drive
Suspension: telescopic forks (front); plunger (rear)
Brakes: 6.7 inch drum (front & rear)
Wheels: 3.50 inch wire (front & rear)
Weight: 375 lb
Maximum Speed: 80 mph.
This is one of two special 500cc R46C machines built for the police in 1948; a keen agent also sold a few 500cc R46C conversions.