In 1917, Henderson sold his company to Excelsior, where he worked as chief designer for two years. But soon disagreements began, and William founded his own company, giving it a resounding name "Ace" ("Ace"). The Ace motorcycle produced in 1919 was very similar to Henderson's first motorcycle, but had a three-speed gearbox, and the working volume was increased to 1206 cm3. And the company "Excelsior" moved in 1920 to the production of the model "Henderson K", designed by Arthur Lemon. The main layout principle - four cylinders in a row longitudinally in the frame - was retained, but the engine was actually redesigned. It became completely bottom-valve, the working volume increased to 1301 cm3, the torque was transmitted to the rear wheel through a three-speed gearbox and chain. William Henderson died in December 1922 when he ran into a new model of Ace motorcycle during a road test. Arthur Lemon became the chief designer instead of him, who designed a number of new high-speed models. A