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Excelsior 750 cm3 Super-X

The Excelsior Super X was a motorcycle manufactured by the Excelsior Motor Manufacturing & Supply Company from 1925 to 1931.[1] It was the most famous Excelsior motorcycle manufactured by that company and was the first American forty-five cubic inch motorcycle.[2]

Excelsior Super X
ManufacturerExcelsior Motor Manufacturing & Supply Company
Parent companySchwinn Bicycle Company
Engineair cooled IOE 746 cc (45.5 cu in) V-twin
Transmission3-speed, chain
Weight450 lb (204 kg) (estimated) (dry)
Fuel capacity3 US gal (with a 1.2 gallon reserve)



Arthur "Connie" Constantine, Assistant Chief Engineer at the Harley-Davidson Motor Company, drew up plans for a mid-sized V-Twin to compete against the Indian Scout. When he presented the unauthorized project to co-founder Walter Davidson, he was reprimanded for wasting the company's time.[3]

Constantine resigned his position at Harley-Davidson and offered his services and his project to Excelsior. Both were accepted, leading to the introduction of the Excelsior Super X in 1925. The design proved to be competitive in motorsports in its first year despite competing against motorcycles with engines of greater capacity.[3]

The Super X effectively replaced Excelsior's other mainstream model, a sixty-one cubic inch V-Twin, which was discontinued during the first year of Super X production.[1] The smaller motorcycle was believed to be a more suitable companion product for their Henderson four-cylinder motorcycle.[4]


The design of the Super X was a considerable departure from its predecessors at Excelsior. Where earlier Excelsiors had an enclosed primary chain transmitting power from the engine to a separate gearbox, the Super X had the engine and transmission together in a single crankcase, using a helical gear to power the transmission directly from the engine.[2][5] The Super X also marked the return of leading-link forks on Excelsior motorcycles, which had earlier switched to trailing-link forks similar to those used by Indian but with coil springs instead of Indian's quarter-elliptic leaf springs.[2][5]

Competition in the marketEdit

The Super X had originally been envisioned as a competitor to the Indian Scout which was, at the time, powered by a thirty-seven cubic inch V-twin engine.[3][6] Indian's initial response to the Super X came in 1927, when they enlarged the Scout engine to forty-five cubic inches. This defensive move was followed a year later with a more decisive attack, the introduction of the 101 Scout.[6] The new Scout proved to be a formidable competitor both on the racetrack and in the marketplace.[4][7]

In 1929, the Excelsior-Henderson concern restyled both its motorcycle offerings, the Excelsior Super X and the Henderson Four, for a more contemporary look.[5] These "Streamline" models had tanks that hid the top tube of the frame and wide front fenders with holes for the forks to pass through.[2]

That year, Harley-Davidson released their forty-five cubic inch motorcycles, the D and the DL.[8]

The Super X competed with the 101 Scout, the D, and the DL, until 1931. During 1931, the Indian 101 Scout was replaced by a Scout model based on the heavier Chief frame, the sport solo DLD was added to the D and DL in the Harley-Davidson line, and the Excelsior-Henderson concern ceased production of motorcycles upon the order of its proprietor, Ignaz Schwinn.[6][8][9]


The Super X was America's first forty-five cubic inch motorcycle, and the racing class for forty-five cubic inch motorcycles was started in the United States one year after the Super X's introduction.[3] The forty-five cubic inch class became the premier class in dirt-track racing, in which such motorcycles as the Indian Sport Scout and Harley-Davidson WR, KR, and XR would compete.

Although the Super X came to an abrupt end, its competitors from Indian and Harley-Davidson would continue for at least a decade.[8][10]


  1. ^ a b Wilson, H. The Encyclopedia of the Motorcycle p. 59 Dorling-Kindersley Limited, 1995 ISBN 0-7513-0206-6
  2. ^ a b c d Wilson, H. The Ultimate Motorcycle Book p. 41 Dorling-Kindersley Limited, 1993 ISBN 0-7513-0043-8
  3. ^ a b c d Pioneers of American Motorcycle Racing by Daniel K. Statnekov, Chapter 22
  4. ^ a b "Antique Motorcycle Museum 1929 Super X Roadster". Archived from the original on 2007-10-08. Retrieved 2007-02-23. Cite uses deprecated parameter |dead-url= (help)
  5. ^ a b c "Excelsior-Henderson History part 7: 1925-1929". Archived from the original on 2007-09-26. Retrieved 2007-02-23. Cite uses deprecated parameter |dead-url= (help)
  6. ^ a b c Wilson, H. The Encyclopedia of the Motorcycle p. 104-105 Dorling-Kindersley Limited, 1995 ISBN 0-7513-0206-6
  7. ^ Wilson, H. The Ultimate Motorcycle Book p. 36-37 Dorling-Kindersley Limited, 1993 ISBN 0-7513-0043-8
  8. ^ a b c Hornsby, Andy. "A Potted History of Harley-Davidson: Part 1 1903-1954". Crewe, UK: American-V. Archived from the original on 2011-02-11. Retrieved 2011-04-04. 1929: Introduction of 30.50ci single, Introduction of 45ci sidevalve V-twin Cite uses deprecated parameter |deadurl= (help)
  9. ^ "Excelsior-Henderson History part 8: 1930-1931". Archived from the original on 2007-09-26. Retrieved 2007-02-23. Cite uses deprecated parameter |dead-url= (help)
  10. ^ Mitchel, D. "Harley-Davidson Chronicle - An American Original" p. 68-69 Publications International Limited, 1997 ISBN 0-7853-2514-X