This is one of the first ever V-twin motorcycles, the Curtiss Hercules which went on sale in 1902, with deliveries commencing the following year. A 20 degree V-twin had been offered by Gottlieb Daimler in 1889, but that was used as a stationary engine, for boats and in the Daimler Stahlradwagen ("steel-wheeled car"), Daimler's second car. Then in November 1902 the UK’s Princeps AutoCar Company offered a V-twin motorcycle, quickly followed by fellow compatriots’ the Eclipse Motor & Cycle Co.’s XL-ALL model and by NSU Motorenwerke in Germany.
But it was Curtiss who led the field, his 50 degree V-twin with Siamesed (knife and fork) conrods looking very much like the designs George Brough would specify for his JAP and Matchless engines 20 years later. Developed specifically for racing, Curtiss took two of his single cylinder Hercules top ends and mated them to a new common crankcase. Mounted inline along the same plane, this new V-twin used a single crankpin with the crankshaft running on roller main bearings. With a 3 x 3 inch (76.2mm) bore and stroke it displaced 42.4 cubic inches (695cc) and produced 5 horsepower while weighing a mere 60lbs (27kg).
For those who could afford it, $150 (when $1000 a year was a typical wage) bought you the V-twin on its own, or you could add a $75 to have it installed in the single’s chassis. To accommodate the heavier and more powerful engine, the wheelbase would be lengthened to 61 inches (155cm) and the frame reinforced with a third top tube and doubled up bottom loop. The reliability of the roller bearings led to their installation in the single, and their use in all Curtiss engines would be a key point in Curtiss' advertising for years to come.
While conceived for racing the twin proved to be refined and well suited to road use, and thus found many happy buyers looking for more power. The V-twin motorcycle would prove to be a happy template, soon adopted as the go-to power plant most notably in the with Indian and Harley Davidson in the US. In the UK Matchless, BSA and Royal Enfield soon had their own V-twins while others used bought in JAP motors to offer some of the finest pre-war motorcycles in the world.
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