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 Magnat Debon - 350 BCP factory 4-bearing
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Magnat Debon BCP factory 4-bearing motocyclette motorrad motorcycle vintage classic classique scooter roller moto scooter
Photo ou archives : D. Ganneau

Capacity : 350
Model : BCP factory 4-bearing
Production : 1935 -
Category : (R) Racing


350 BCP "Four-bearing" · 1936

A classic French racer

Based in Grenoble, Magnat-Debon was an early participant in motorcycle sport. As early as 1906, a Magnat-Debon won the grueling Mont-Ventoux hillclimb. During the 1920s, after the marque had combined with Terrot, Paul Boetsch kept on winning with Blackburne-engined machines. In 1932, Terrot announced that it would be selling client-competition machines. It was possible to buy these badged as Magnat-Debons.

Mountain Marque

At the same time, Magnat-Debon (whose Edelweiss badge celebrated its birthplace in the Alps) continued to race specially-built competition machines like the 350 BC, with Jacques Onda as official works rider.

Rapid Development

Between the first "CP" racer of 1932 and the 1936 BCP illustrated, many components were changed. The gearbox, initially a Burman unit, had become an own-make item. The aluminum crankcase and two-bearing crank were replaced by a magnesium crankcase and a crank whose stroke had been reduced by 10 cm and which now ran in four rollerbearings. The shorter cylinder was deeply recessed into the crankcase and was crowned by a re-engineered cylinder head. Finally, the adoption of stunning tanks altered the look of post-1936 racing Magnats. With superb road handling, the BCP had one of the finest gearboxes of its day. It was lightweight and powerful in braking, and its sole drawback was its tendency to run big-ends at high speeds. That meant it was best on winding tracks like Mont Ventoux, where Jacques Onda won in 1936.


Engine: 344cc (74x80mm) air-cooled singlecylinder four-stroke; dry-sump lubrication

Power Rating: 30 hp @ 6500 rpm

Valves: overhead

Fuel System: ca rburetor

Transmission: 4-speed foot shift, multi-disc dry-clutch; chain final drive

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

Brakes: 6.7 inch drums (front & rea r)

Wheels: 3.00x21 inch (front); 3.50xl9 inch (rear)


The stunning elegance of the "four-bearing" Magnat-Debon BCP makes it one of the finest French racing bikes and a world-class classic.

Le fichier Moto Passion réalisé par François-Marie Dumas réunit près de deux mille photos accompagnées d'un historique très complet des machines présentées.
Il sera progressivement mis à jour ici et toute information complémentaire est la bienvenue sur info@moto-collection.org.

Cette documentation unique, qui constitue sans doute l'encyclopédie la plus exhaustive jamais écrite sur l'histoire de la moto, a été réalisée avec l'assistance de nombreux spécialistes dont principalement Didier Ganneau, Christophe Gaime, Mick Woollett, Jean Goyard, Bernard Salvat, Christian Rey, Yves Campion, Helmut Krackowizer, Michael Dregni, Michel Montange, etc. que je remercie ici.

Disponible sur demande :
- Les fiches originales sur papier
- Les photos et archives signées de mon nom en haute définition ou les documents originaux.
Me contacter sur info@moto-collection.org pour les conditions et droits d'utilisation.