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 Monark - 500 GP Crescent e/g
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Photo ou archives : F-M. Dumas

Capacity : 500
Model : GP Crescent e/g
Production : 1973 -
Category : (R) Racing


500 Grand Prix I Rudi Kurth -1973

The smallest Grand Prix 500

The start of the 70s marked a turning point in the development of world championships. The Japanese factories arrived in force; it was the last hurrah for the little builders and tuners. A few short years later, only the works machines remained.

Cash-Strapped Constructor

Rudi Kurth was one of the cheery but cashstrapped rider-constructors who added so much ro the atmosphere of those old-time GPs. This sidecar champion, who lived on the circuits in his Citroen DS wagon, began work on a 500 in 1973. Inadequate preparation meant that it never finished in the money, but it remains one of the more interesting machines of its day.

Monark Track Racers

The Monark company, best known in off-road competition, also took part in track racing. In 1972 it created, under the guidance of Billy Andersson, a racing 500 of classic design- apart from its engine. Derived from a boat engine, it was a compact Monark-Crescent three-cylinder two-stroke developing 75 hp. Kurth continued its development as a solo motorcycle power unit and built a 500 which, for size and style, looked more like a 50cc racer! It weighed less than 220 lb and its twisted shape was molded around its rider. Cooling is a critical problem for a marine engine, so the power unit - suspended below the frame - was cooled by three water pumps. The fitting of variable volume mufflers cut maximum power by some 6 hp compared with the marine version.


Engine: 500cc water-cooled three-cylinder

Power Rating: 75 hp @ 12,000 rpm

Valves: two-stroke

Fuel System: three Tillotson carburetors

Transmission: 5-speed; hydraulic clutch;

chain final drive

Suspension: telescopic forks (front); swinging arm (rear)

Brakes: twin disk (front); disk (rear)

Wheels: spoked alloy (front & rear)

Weight: "less than 220 lb"


The astounding Monark-Crescent-powered racer of Rudi Kurth weighed as little as a 50cc machine.

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.