Aermacchi Harley-Davidson 250 Wisconsin/Sprint/SS
Years Produced: 1961-1968
Power: 16-25hp
Top Speed: 80mph/90mph (claimed)
Engine: 246cc (66mmx72mm), 248cc (72mmx61mm) air-cooled OHV single
Transmission: 4-speed, chain final drive
Weight (dry): 261lb/271lb/281lb
Price then/now: $750 (1967)/$3,000-$8,000
If longevity, versatility and development potential count for anything, Alfredo Bianchi’s 1956 design for a stylish 175cc commuter bike should be considered one of the best. Though the Aermacchi Chimera was a flop, Bianchi’s simple OHV powerplant doubled its displacement over two decades, took Renzo Pasolini to second place in the 1972 250cc world championship, and launched the flat-track careers of Cal Rayborn and Gene Romero. Sixty years on, it’s still a weapon of choice in AHRMA Sound of Singles racing.
Harley-Davidson may have seen this potential when they bought 50 percent of Aermacchi in 1960. With sales of its big twins faltering, the Motor Company decided that Aermacchi’s touring 250cc, the Ala Bianco (white wing) would sell well in the U.S., and certainly beat out their existing small-bike offering — the obsolete 165cc 2-stroke Super 10. So the Ala Bianco was imported into the U.S. with minor changes as the 1961 Harley-Davidson 250 Wisconsin.
Bianchi’s engine followed general Italian practice in having a built-up crankshaft with ball main bearings and a roller big end. The oil-bearing crankcases split vertically. A chain turned the camshaft which operated the overhead valves by pushrods and rockers. A 24mm Dell’Orto carburetor provided fuel, which was sparked by a 6-volt battery/coil ignition system. Bevel gears transferred output to the wet clutch and 4-speed gearbox. The engine hung from a stout spine tube frame with a telescopic front fork and dual rear spring/damper units. Brakes fitted to the 17-inch wheels were single-leading-shoe front and rear. With 8.5:1 compression, the “long stroke” (66mm x 72mm) engine made 16 horsepower.
In spite of a number of continental quirks — the kickstarter on the left side, and kickstand on the right — the 250 was well received and sold in increasing numbers.
The Wisconsin lasted just two seasons. For 1963, it became the Sprint C with power increased to 18 horsepower, good for a top speed of around 80mph. It was joined by the sportier Sprint H with 9:1 compression, 21 horsepower and 18-inch wheels. The H sported an industrial-size air cleaner can where the C model’s toolbox had been and could be ordered with a high or low exhaust system. The H quickly became the more popular model, outselling the C by at least 5:1. The engine’s tuning potential was demonstrated in 1964 at Bonneville, when a 250cc streamliner recorded over 150mph, then stretched that to 177mph in 1965.
1967 brought an engine redesign, creating the “short stroke” 250. An aluminum cylinder of 72mm bore replaced the cast iron item, and combined with a shorter, 61mm stroke for 248.4cc and a power increase that H-D claimed to be “18 percent.” The new engine was also intended to reduce oil leaks and ease maintenance by using a one-piece valve cover. The C model was dropped in favor of a new street scrambler, the SS. The H continued with the new engine, but was handily outsold by the SS.
The SS employed a smaller gas tank, 19-inch front wheel, “high boy” fenders and a tachometer; while the lighting equipment became quickly detachable for off-highway use. (Though for serious competition, versions of the 250 in road-race and off-highway trim had been available as the CR, CRS and CRTT.)
1968 was the last year for the 250, and it was replaced for 1969 by the 350cc street SS350, and in 1971, the trail bike SX350. But it carried over many of the 250’s anachronistic features, like the overhead valve layout, kick-only starting, 4-speed transmission, 6-volt lighting and single-leading-shoe brakes. Its Japanese competition now featured twin-leading-shoe brakes, overhead cams, 5-speed transmissions and electric start. A 5-speed gearbox finally arrived in 1973 — but by then it was too late. H-D parent company AMF sold Aermacchi (and its Varese factory, where MV Agustas are now produced) to Cagiva in 1978.
Cycle magazine summed up the 1967 250 Sprint SS, “… we will simply say that it has brakes and handling that are beyond reproach, and that it feels … like no amount of flogging will hurt it.” MC
1964-67 Triumph T20SM Mountain Cub
Years Produced: 1964-1967
Power: 15hp @ 6,500 rpm
Top Speed: 60 mph (approx.)
Engine:199cc(63mmx64mm) air-cooled OHV single
Transmission: 4-speed, chain final drive
Weight: 250lb (wet)
Price the/now: $2,000-$8,500
Like many of the best Triumphs, the Mountain Cub was conceived in the U.S. — in this case as a trail bike intended to out-perform Honda’s Trail 90. It married the T20S Sports Cub engine with wide-ratio gears from the TR20 Trials Cub. The factory added a tucked-in exhaust and Dunlop Trials Universal tires. An initial order for 400 units was snapped up: “We sold every one we could get,” said Johnson Motors’ Don Brown at the time, “and could have sold twice as many.” Accessories included a rifle rack, cross-braced handlebars and an oversized rear carrier.
Cycle World tested one in 1964, declaring it the trail bike they’d been waiting for: “… a real motorcycle, slightly undersized, properly equipped and geared.” It handled easily, steered quickly, and was “downright comfortable” on rough terrain, they said. Though basically reliable, Mountain Cubs suffered from a weak engine bottom end, not helped by the notorious “ET” (energy transfer) ignition, which required careful setup and frequent adjustment.
The Mountain Cub fell victim to BSA/Triumph rationalization, which moved Cub production to BSA’s Small Heath factory. The final Cubs used a BSA Bantam chassis and cycle parts.
1961-1967 Honda CL72
Years Produced: 1961-1967
Power: 24hp @ 9,000rpm
Top Speed: 87mph (period test)
Engine: 247cc (54mmx54mm) SOHC air-cooled
Transmission: 4-speed, chain final drive
Weight: 315lb (wet)
Price then/now: $690 (1962)/$3,000-$12,000
Honda’s CL250 was more off-highway focused than the Sprint H/SS, with braced handlebars, 19-inch wheels and high level exhaust. Compared to its sibling CB250 street bike, the CL omitted the front TLS brake and electric starter — but neither were available on any of the H-D Sprints.
Common to the CB and CL models was a SOHC parallel-twin engine with a built-up, 180-degree crankshaft driving both the camshaft and clutch by chain. Battery/coil ignition sparked mixture from two 22mm Keihin carbs. The wet-sump crankcase was split horizontally and also contained the 4-speed gearbox. The CL72’s engine slotted into a closed loop tubular frame with a single downtube (open loop on the CB). A hydraulic steering damper was a stock fitment.
Cycle World was duly impressed with the CL72’s power delivery. “It will pull strongly almost from idle, and when those revs begin to gather, it will really storm along,” CW said, and also praised its handling: “… outstanding was the Honda’s behavior on more firm dirt and clay.” Noting that at that time Honda built some 85,000 motorcycles a month, CW concluded, “…careful mass-production is the reason for the Honda’s neat and clean appearance, and its very reasonable price.”
