The fabled Harley-Davidson Sportster was developed from a smaller and fairly unpopular Harley called Model K that was built from 1952-56. It was aimed at the European imports but failed to gain favor as did similar efforts by Indian. The 45 cubic inch side-valve V-twin engine developed 30 bhp, and despite being lightened it was difficult to reach 80 mph.
The issue of performance was very much resolved in 1957, however, with the introduction of the overhead-valve XL Sportster. The 883 cc engine now produced 40 bhp and the engine and gearbox were unit construction, with the latter easily accessible through a side cover. The rear shocks were of the automotive type and even gave enough travel for off-road use. Further improvements in 1958 to the engine included higher compression, domed pistons, larger ports, and larger valves. The XLCH model (Competition Hot) had high pipes, a magneto-generator ignition, peanut gas tank and semi-off-road tires. By 1959, high-lift cams could push a Sportster to 115 mph, and the quarter mile was possible in under 14 seconds.
In 1961, Hi-Fi colors offered endless combinations, and staggered shorty exhausts arrived in 1962. Fork brackets and motor mounts were available in alloy in 1963, and alloy front hubs were fitted in 1964. In 1965, the Sportster got a 12-volt ignition, and electric start and new front forks followed in 1968. That year the motor produced 58 bhp. A wet clutch followed in 1971 and the V-twin was punched out to 1,000cc in 1972, approaching 70 bhp.
Harley-Davidson caught lighting in a bottle and the rebellious image caught the public’s imagination and kept the imports at bay. It’s been a mainstay of the Harley range continuously since its introduction in 1957, and many of the more performance-oriented bikes built by Erik Buell have been based on Sportsters. The image of a low-slung sportster cruising the Interstate is about as American as apple pie.