the AJS Porcupine, a 500 cc forward-facing parallel twin, and the AJS 7R (32 bhp, 350 cc OHC single) were being raced alongside their AMC stablemates the Matchless G50 (effectively a 500 cc 7R) and by 1951, the Matchless G45 (a 500 cc vertical twin). The AJS Porcupine had been designed for supercharging, before the rules changed banning supercharged racing motorcycles, but even so, Les Graham won the 1949 World Championship on an unsupercharged AJS E90 500 cc Porcupine. In 1951 AJS development engineer Ike Hatch developed a 75.5 mm bore × 78 mm stroke, three-valve-head version of the 7R making . It was called the AJS 7R3, and was Ike's response to the Italian multi-cylinder racers. They did well enough in their first year, not as well the second. For 1954 Jack Williams, the works team manager, developed the bike further, lowering the engine in the frame, and making some tuning changes that gave @ 7800 rpm. It immediately won the first two rounds of the World Championship and took first at the Isle of Man TT. These were factory specials, but one has survived, and a second has been reconstructed from spares. AMC withdrew from the world of works and one-off road racing at the end of the 1954, with the death of Ike Hatch, and in the face of fierce competition from the other European bikes. After this AJS made a production version of the standard two-valve AJS 7R, for privateers. In 1954 Norton was also moved to the Plumstead works. With the G15 line, AMC had built on the merits of the G12 but there were numerous changes to frame, forks, swinging arm, primary chaincase, transmission, cycle parts and lubrication system. The P11 was the last line of bikes with bonds to AMC. It used a modified G85CS frame but there were stronger forks, completely new cycle parts (making some was rather costly), altered lubrication and modified primary chaincases, to mention a few. The G15 series was offered as 3 brands: Matchless G15 comprising G15Mk2, G15CS and G15CSR; AJS Model 33 comprising M33Mk2, M33CS and M33CSR; and last not least Norton N15CS (no Norton-branded roadster made as it would compete against the Atlas). The G15 series was produced from 1963 to 1969. They were initially for export only, but by 1965 these models were available in UK and Europe too. Associated Motorcycles and the AJS name