1954 AJS E95
Engine: 498cc air-cooled DOHC parallel twin with cylinders at 45 degrees, 68mm x 68.5mm bore and stroke, 9:1 compression ratio, 54hp @ 7,800rpm (est.)
Top speed: 143mph (Isle of Man, 1964)
Carburetion: Two 1-1/8-inch Amal GP
Transmission: 4-speed, right foot shift, chain final drive
Electrics: Lucas magneto ignition
Frame/wheelbase: Dual-downtube steel cradle/56.5in (1,435mm)
Suspension: AMC Teledraulic telescopic forks front, dual AMC Jampot shocks rear
Brakes: 8in (203mm) TLS drum front, 8in (203mm) SLS drum rear
Tires: 3 x 19in front, 3.50 x 19in rear
Weight (dry): 335lb (152kg)
Seat height: 28in (711mm)
Fuel capacity: 6.5gal (19ltr)

To understand the importance of this 1954 AJS motorcycle, you have to go back more than 60 years, to the closing days of World War II and the pent up energy within the British motorcycle industry to go racing again.

While the industry had kept busy manufacturing whatever machinery the War Department deemed necessary to defeat Hitler’s Germany, building motorcycles was at the core of companies like AJS. With fond memories of the commerce and competition of pre-war days, AJS was ready to get back to what it did best.

AJS E95 beginnings
A few years before WWII, AJS developed a water-cooled, supercharged, double-overhead-cam 500cc racing V4.

A technological tour de force, it was extremely complex, and also quite unreliable. Although it failed to perform as well as hoped, it did set a record 100.01mph average lap time at the 1939 Ulster GP, a first on a road circuit.

The V4’s only other significant performance came seven years later, when Jock West rode it to victory in the 1946 Belgian GP. A few months later FIM, the international race governing body, banned supercharging, and at a stroke the V4 became just another old race bike. The FIM ban also affected plans for a new AJS engine already in the works.

By early 1946, AJS had a new horizontal, parallel-twin 500cc racing engine in development, and like the V4 it was also to be supercharged and water cooled. Following FIM’s ban, the new E90S (“E” for experimental and “S” for supercharged – the “90” designation harkened to an earlier Sunbeam racer, a brand owned by AJS parent company AMC) was reworked to naturally aspirated, air-cooled form. The result was the now famous 1947 AJS E90 “Porcupine,” so named for the distinctive, heavily spiked cooling fins on its air-cooled cylinder head.

The E90 was campaigned and developed over the next five years. Its major moment of glory came in 1949, when Les Graham won the inaugural 1949 500cc World Championship riding an E90. He was the first winner of the series and the AJS would become the only twin to ever win the 500cc championship.