The AJS Porcupine won the inaugural 1949 500cc Grand Prix world championship for rider Leslie Graham.
The Porcupine was an unusual AJS racing motorcycle with a supercharged, horizontally opposed twin-cylinder engine. The nickname referred to the prominent cooling fins around the cylinder heads, which suggested a porcupine’s spines.
The 1949 championship was the first season organized by the Fédération Internationale de Motocyclisme as a world championship series. Graham secured the 500cc title on the AJS, making him the first 500cc motorcycle world champion in the new system.
The Porcupine’s supercharger was later prohibited under changing Grand Prix rules, and AJS did not enjoy the same long-term dominance as Norton or Gilera. That helps explain why the bike is less familiar today despite its historic first championship.