Alcyon - SS 4 HP Super Sport
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Alcyon  D2-492-66-16
Photo ou archives : F-M. Dumas

Capacity : 350
Model : SS 4 HP Super Sport
Production : 1928 -
Category : (R) Street Bike


350 Supersport – 1928

Twin-cam rarity

Influenced by the Bud1et engines that it had fitted since 1904, Alcyon was among the first motorcycle makers to opt for overhead-valves, initially in racing - with four valves in 1912 - then on its catalogue models in 1927.

Obscure Origins

The origins of the Alcyon marque are obscure. All that is known is that the firm, based in Courbevoie (Paris), was owned by the Gentil family and began, like many other companies, by making bicycles. But the actual connection between Zürcher of Courbevoie and the ancient firm of Zürcher & Luthi (ZL) from Saint-Aubin (Switzerland) - and later known as Zedel with a branch company at Pontarlier – is unknown.

Advanced Engine

It's likely, however, that Zürcher of Courbevoie was the fruit of the acquisition of Zedel-Pontarlier by the Gentil family in 1923. It's definite that, in 1924, Alcyon began exclusively fitting Zürcher engines, first two-strokes and then, in 1927, three four-stroke units of 175, 250 and 350cc. All these Zürchers were single-cam pushrod engines with external flywheels, single exhaust pipes and hemispherical cylinder heads. Alongside these engines there was also a two-cam pushrod Zürcher 350 with internal flywheels. This was fitted, with a forward-mounted magneto by Thomann and Labor (two marques belonging to the Gentil group), but not a single Alcyon catalogue depicts a machine so equipped. It nevertheless existed, and at least two twin-cam Zürcher-powered Alcyons survived, though with rear-mounted magnetos.


Engine: 346cc (70x90mm) air-cooled single-cylinder four-stroke

Power Rating: 10 hp

Valves: overhead

Fuel System: carburettor

Transmission: Bridier-Charron 3-speed, multi-plate clutch, chain final drive

Suspension: leading-link forks with friction dampers (front); rigid (rear)

Brakes: drum (front & rear)

Wheels: wire (front & rear)

Weight: 198 lb

Maximum Speed: 60 mph

Not featured in the Alcyon catalogue, this Zürcher-powered Alcyon with internal flywheels is an exceptionally rare and elegant machine.

Motorcycle encyclopedia Moto Passion, realised by François-Marie Dumas, include almost 2000 photos presented with an exhaustive history of the motorcycles exhibited.

This unique collection has been realised with the participation of many specialists. With many thanks in particular to Yves Campion, Michael Dregni, Didier Ganneau, Jean Goyard, Helmut Krackowizer, Michel Montange, Christian Rey, Bernard Salvat, Mick Woollett, etc

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