In production from 1958 to ‘62, the allure of the G50 Matchless was simple: it was a 500cc, air cooled, single cylinder, four stroke machine that was competitive, inexpensive, and easy to maintain. A derivative of the 350cc AJS 7R engine that was created in Britain in the post war 1940s, the G50 returned to prominence in the 1970s when resurgence in national and international classic racing took hold.
The engine cutaway picture, prepared by former G50 racer Chuck Huneycutt, who heads the restoration division at the Barber Motorsports Museum, allows viewers a unique insight into most of the functioning parts behind the magnesium Elektron alloy castings. Elektron was used to save weight and the anodized gold finish was used to protect it from oxidizing.
Unsurprisingly, under George Barber’s development and racing program of the 1990s the G50 was transformed. With Huneycutt’s influence peak power increased by over 25 percent. The single Amal carburetor was replaced by a 44mm Mikuni VM round-slide-style. Although the original Amal produced slightly more power at full throttle it had a tendency to hesitate while cornering at maximum lean. Most notably, as the compression ratio, engine rpm, and power output increased, the original 35-tonne-steel flywheel, now working beyond its design capability, began to crack. The solution was to replace the original design, a pressed-together crank, with a one-piece style. Further development involved the addition of a second spark plug, which led to a reduction in ignition timing. As a result maximum power occurred at 18 degrees before TDC instead of the original 32-degree setting.
Though in low resolution, the deftness of the G50 can still be enjoyed in action on the public roads of the Isle of Man TT circuit. Resurrecting its deep sounds, here is fascinating G50 footage with the remarkable Dave Roper on board. Roper, who won the 1984 Senior Historic TT – the first American to win on the Isle of Man – displays his prowess on the twisty, bumpy B-roads of the formidable 37.75-mile course that includes 250 bends and corners.