Stuart Turner - Stellar
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Stuart Turner D2-492-78-13
Photo ou archives : M. Woollett

Capacity : 750
Model : Stellar
Production : 1912 - 1914
Category : (R) Street Bike


750 Stellar - 1912

From steam to gasoline

The Stuart Turner factory in Henley-on-Thames was the first to produce small steam engines for private launches. In 1912, it staggered the motorcycle world by unveiling a large-displacement two-stroke at the time of the Olympia Motorcycle Show.

Big Ideas

After experimenting with a 300cc two-stroke single intended to power a motorboat, the marque had decided to build a bigger gasoline engine for the motorcycle market.

Tandem Twin

The new machine was powered by a water-cooled tandem twin that drove a two-speed gearbox bolted to its rear, through a 30-plate dry clutch. Gears were shifted by the left hand, while the clutch was operated by the right foot. Final drive was by shaft and endless worm gear, and the machine was started by an automobile-type crank handle carried aboard the machine that engaged with a shaft projecting from the gearbox. The lubrication was not by a gas/ oil mixture like most two-strokes, but oil contained in a compartment in the crankcase was forced out by pressure created by the descending piston and into the upper part of the engine. The prototype (probably the only Stellar ever built) was fitted with a sidecar and used during major military maneuvers in 1913, but no orders were forthcoming, and the project was abandoned when WWI began the following year.


Engine: 743cc water-cooled tandem twin

Power Rating: 8 hp @ 1680 rpm

Valves: two-stroke

Fuel System: Senspray carburetor

Transmission: 2-speed, multi-plate dry-clutch; shaft-and-worm final drive

Suspension: Druid laterally-sprung girder forks (front); rigid (rear)

Brakes: cycle-type rim (front); belt rim

Wheels: 3.00x26 inch (front & rear)

Weight: 260 lb

Maximum Speed: 45 mph

Famed for its steam launch engines, the Stuart Turner factory built the Stellar in 1912, but this project for a big two-stroke motorcycle never passed the prototype stage.

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

One can order here

  • Original cards on paper (in french)
  • High resolution scans or original documents presented and signed with my name.

Please contact me at for conditions and copyright.

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François-Marie Dumas

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