The 1937 Indian Four was one of the first four-cylinder two-wheelers ever to be produced. This machine is one of the predecessor of the modern-day, big-bore touring motorcycles, and was one of the most comfortable and long-haul oriented machines of its time. It came standard with a hardtail rear suspension, laced wheels, a dual exhaust system, pull-back handlebars and a single seat. Also, this was the first year when Indian introduced a new engine, an upside-down four-cylinder one, that produced a claimed 35 horsepower at 3600 rpm.
The 1933 Indian Four was one of the most powerful two-wheelers of its time, as well as one of the most expensive ones. It boasted an estimate 30 horsepower from its air-cooled, in-line four cylinder powerhouse, and could reach a top speed of 75 mph. Also, it came with a solo seat, laced wheels, rider floorboards, a hardtail rear suspension, and a large, 4.6-gallon fuel tank.
In 1927, the right, the name and production facilities were purchased to the Ace Motor Corporation, so, all the products were sold under the Indian Ace name for one year. The Four model had a lot of success and the company tried to develop the engine on that period. The 1936-1937 models were not so popular because of the "upside-down" engine but one year later the company returned to the original configuration that made this bike so appreciated. Unfortunately, the Indian Four ended its career in 1943