Supercharged AJS 500 V4 (1939
By 1930s Brit-bike standards, the AJS 500 V4 was pretty fancy. The bike was fitted with a liquid-cooled, SOHC, 8-valve, 495cc V4, with a chain-driven Zoller supercharger. With 55 horsepower at 7,200rpm (with the compressor running at 16.5psi boost pressure) and a dry weight figure of 183 kilos, the supercharged AJS 500 could hit a top speed of up to 216km/h, which must have been pretty scary if you take into account the feeble drum brakes and the not-so-evolved tyre technology of that era.
British journalist Alan Cathcart had the opportunity to ride the only surviving AJS 500 V4 during the Goodwood Festival of Speed, in England, a few years ago. Here are a few excerpts from what he has to say about the machine:
Starting it is an acquired skill. You have to prime the supercharger to get it to fire, so starting from cold requires a long-distance push with the throttle held wide open. Eventually the engine starts burbling into life, before suddenly catching and emitting a high-pitched rumble from the four megaphones bracketing the rear fender. You then have to blip the throttle furiously to keep the plugs clean, all the while aware of the muted whine of the Zoller compressor as a background accompaniment to the engine’s organ concerto.
The AJS’ supercharged engine pulls lustily from under 2,000 revs and feels surprisingly modern and sophisticated. In spite of the lack of a counterbalance, there’s no undue vibration and no vintage-style rattles and whirrs or extraneous mechanical noise.
In tighter turns, the AJS swings more readily through the bends than bulkier inline-fours like the 1950s Gilera and MV Agusta 500s I’ve ridden. It’s not as agile as a single but no heavier-handling than a twin. But that’s in slower turns. Elsewhere, the AJS V4 is a real handful, especially in a straight line. Indeed, riding the AJS 500 V4 made me realize you must re-learn your riding technique to ride it. Basically, there’s no such thing as part-throttle – the throttle must either be wide open or switched right off. Try it and it splutters until the throttle is wide open again. Brake, point, squirt – that’s the secret to supercharged success.
SOURCE: Faster and Faster