Harley Davidson - S Flat track
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Harley Davidson D2-492-48-15
Photo ou archives : H. Ludwig

Capacity : 564
Model : S Flat track
Production : 1917 -
Category : (Off-Road) Speedway & other


35 ci Flat Track Racer - 1917

A winning technique


William S.Harley, the designer, and Arthur Davidson completed their first motorcycle in in 1903. It incorporated the best current technology and proved strong and reliable enough to attract a growing band of customers. They built a factory and brought in Davidson's two brothers to assist in what was formalized as the Harley-Davidson Motor Company in 1907.


Demand for More Power

In response to the demands of the clientele, who were always asking for more power, and as a riposte to the launch of a 430cc Indian racing single in 1905 (followed two years later by a production version), Harley brought out a new 564cc (84x102 mm) single in 1907.


Racing Program

It developed 4 hp and was good for 50 mph. It was joined in 1909 by an 880cc V-twin capable of 55 mph. The single was redesigned in 1913 with magneto ignition, dual-ratio chain drive with a hub clutch and the remarkable Harley leading-link front fork. Built to high standards of quality, it used vanadium steel in its construction as did another contemporary American icon, the Model T Ford – and cost just $235. Though Indian was still the sales leader, Harley-Davidson was coming up fast – aided by the many wins achieved by private owners in races and endurance runs, though the factory refused to back a competition program until 1913, when William Ottaway was recruited from Thor. He developed a catalogue racer, the II-K V-twin (which gained 8 valves in a Ricardo head in 1915) from which a single was born. It was rare (30 built) and costly; many private owners preferred to build their own racers around production Harleys, like this well-preserved 1917 flat-track racer.



Engine: 564cc (84x102 mm) air-cooled single-cylinder four-stroke; total-loss lubrication with mechanical pump; magneto ignition

Power Rating: 5 hp

Valves: "pocket" overhead intake, side exhaust

Fuel System: carburetor

Transmission: direct chain drive

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

Wheels: 28 inch wire clincher (front & rear)


This 35 ci, shown on a West Coast flat-track, was converted in 1917 out of a standard "Silent Gray Fellow" roadster with a pocket-valve power unit.


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 info@moto-collection.org for conditions and copyright.

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François-Marie Dumas

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