 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.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.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.