AMA Motorcycle Hall of Fame | Where Heroes Live On
First Name
Last Name

Arthur Constantine


Engineer, Designer for Indian Motocycle Co. and Excelsior-Henderson Motorcycles

Born in 1891, Arthur “Connie” Constantine was one of the most preeminent motorcycle engineers of the 1920s. A lifelong motorcyclist and engineer, he was initially employed by the Buick Division of General Motors until 1920, when he was offered the position of assistant chief engineer at The Harley-Davidson Motor Company. His resume included work on many chassis and engine development projects, including Harley-Davidson’s potent eight-valve racing engine.

While in Harley-Davidson’s employ, Constantine worked on an unauthorized design project for a new mid-sized V-twin engine that could compete against rival Indian’s famous Scout. However, his design was condemned by Harley leadership in 1924 as a “waste of valuable company time.” As a result, Constantine left Harley-Davidson shortly thereafter.

With his design work in hand, Constantine approached Excelsior with his concept for a unit-construction motor, one in which the engine and transmission shared the same crankcase. Unveiled in 1925 as the 45-cubic-inch Excelsior Super-X, the new motorcycle became an astounding success both in the showroom and on the track.

Constantine’s best work would result in one of the finest four-cylinder motorcycles ever to grace the roads. Excelsior also owned Henderson, and Constantine reviewed the famous Henderson DeLuxe motorcycle. He came to the conclusion that a radical redesign was the only course of action that would improve the machine. His masterpiece, the Streamline Henderson KJ, was unveiled in March 1929. The motorcycle boasted 57 new features and developed 40 horsepower at 4,000 rpm. The motor design reverted back to the overhead intake valve arrangement, but incorporated a five-bearing crankshaft, improved pressurized oiling and a down-draft intake manifold. The chassis positioned the saddle lower, and used streamlined saddle tanks. The motorcycle was guaranteed to hit 100 mph.

In the late 1940s, Indian Motorcycle Company retained Constantine as a consultant on the development of the new Indian Arrow and Warrior models. He was subsequently hired as chief engineer and vice president of Indian.

Constantine died in 1973. He was inducted into the AMA Motorcycle Hall of Fame in 1998.