PORCUPINE
A true screen deflects the wind on this most exotic AJS racer.
Here in all its dark, fluid grace is the AJS Porcupine, a parallel-twin that was England’s postwar bid to rise above the limited power of traditional British racing singles with more cylinders and higher revs. In 1949— the first year of the new FIM world championships— rider Les Graham would give the Porcupine its only championship. The bike in these photos was not the championship-winning 1949 E90, but rather the last redesign in 1954 with 45-degree-inclined cylinders.
The name—Porcupine—originated with the quill-like spike finning between the pair of cam covers of the original engine, whose cylinders were just 15 degrees above horizontal.
In the 1920s AJS had led the high-tech development of overhead-valve and then overhead-cam racing singles in the Isle of Man TT races. The Collier brothers, who joined AJS, Matchless, and Sunbeam into Associated Motor Cycles (AMC), had themselves been pre-World War I TT winners.
The Porcupine’s usual origin story is that it was sketched on napkins during teaIrving says in his autobiography, was “mainly the design of a racer-type named E90S, the ‘S’ standing for ‘Supercharged.’”