The AJS E95, nicknamed the “Porcupine”, illustrates how a rule change can reshape a racing motorcycle. Its E90 predecessor had been conceived when supercharging was still allowed. After the Second World War, racing regulations banned superchargers and the earlier design became uncompetitive. Introduced in 1952, the E95 was a substantial reworking of this unusual twin-cylinder machine for the new conditions.
The most distinctive alteration was to set the cylinders at a 45-degree angle. This shortened the wheelbase and was intended to improve handling, a crucial advantage on a circuit where engine output alone is not enough. The bike used a 498 cc air-cooled twin with double overhead camshafts, a four-speed gearbox and chain final drive. The “Porcupine” nickname came from the pointed cooling fins of the earlier engine, which gave it a bristling appearance.
The E95 was fast, yet persistent reliability problems prevented it from becoming a lasting racing solution. In 1954 it was replaced by the G45 twin, based on the G9 road motorcycle. The E95 now stands as a vivid example of engineers changing the whole machine to recover an edge after the rules moved. The museum’s example won first in class at the 2009 Pebble Beach Concours d’Elegance.