THE ACE IN-LINE 4 MOTORCYCLE ENGINE
Founded by William G. Henderson in 1920, the Ace Motor Corporation began manufacturing high-performance inline four-cylinder motorcycles that were styled after Henderson’s compelling Excelsior-Henderson Model F and Model G inline-fours. Henderson’s goal was to build the fastest motorcycle in the world, and the first bikes produced by Ace were a series of five experimental four-cylinder engines known as XP1 through XP5.
By early 1923, Charles ‘Red’ Wolverton defected from Excelsior-Henderson to become Ace Motor Corp’s chief test-rider. To aid in the tuning of their magnesium-cased engines, Ace was one of the first motorcycle manufacturers to use a brake dynamometer to extract every ounce of horsepower. According to Wolverton, their first engine blew up on the dynamometer, sending the magneto past his ear. The management at Ace was so confident in their new engines that they put up $50,000 to any other motorcycle manufacturer who could beat their bikes.