The AJS Porcupine won the first 500 cc Motorcycle World Championship for its manufacturer in 1949.
AJS rider Leslie Graham won the inaugural 500 cc world championship aboard the Porcupine. The championship was organized by the Fédération Internationale de Motocyclisme and formed the premier class of the new motorcycle Grand Prix series.
The Porcupine used a supercharged, air-cooled parallel-twin engine. Supercharging was permitted in the early championship era, although the technology was soon restricted in Grand Prix racing because of its performance advantages and complexity.
The motorcycle’s name referred to the appearance of its finned cylinder heads. The AJS Porcupine is distinct from the later Norton Manx, which became one of the dominant naturally aspirated machines of the 1950s.