Engine: Single cylinder, 2-stroke
Bore & stroke: 38.8 x 42 mm
Compression ratio: 7.8:1
Engine Capacity: 49.6cc (3.03 cubic inches)
Maximum power: 1.5 h.p. @ 4,500 rpm
Valves per cylinder: 2
Ignition type: Dynamo - 6 volts - 18 watt
Carburettor: Dell'Orto SHA
Lubrication: Wet sump forced circulation with mechanical gear pump
Transmission: Gear primary, chain final
Clutch: Cable operated with multiple wet disk
Gearbox: 3-speed, gear shift
Throttle: Cable operated
Cooling system: Air cooled
Frame type: Tubular pressed steel and backbone frame
Front Suspension: Telescopic
Rear Suspension: Mono shock, Swingarm
Front Brake: Drum
Rear Brake: Drum
Front tyre: 2.00 x 18 in.
Rear tyre: 2.00 x 18 in.
Wheelbase: 44.1 inches
Seat: Duck-tail dual seat
Fuel tank capacity: 6 litres
Top speed: 45 km/h
Weight: 52.5 Kg
Price in 1966: US$275 plus tax
In 1960, Harley-Davidson acquired 50% of the Aermacchi factory and assumed complete control in 1974. Harley-Davidson purchased Aermacchi in 1961, to produce lightweight motorcycles for the American market, in an attempt to capture a piece of the youth market back.
In 1965, Harley-Davidson brought a smaller two-stroke Aermacchi onto the market, the Zeffiretto. The name "Zeffiretto" was used for the Italian market. This 48cc machine came as a moped, the 48NP (P for pedals) and without pedals, a no-ped, hence 48N with no P. The engine is 38x42mm, plain piston-port, CR 8.5:1, with 3 speeds actuated by a hand shift. The 48NP was built until 1965, whilst the 48N continued until 1972.
In the United States Aermacchi sold these motorcycles as the "Harley-Davidson M 50 and M 65". The Zeffiretto / M 50 and M 65s were virtually unmarketable in Europe and in America, despite large advertising campaigns. In total only 200 examples of this rare Aermacchi Zeffiretto Sport 48 S (M50S) were built.
Bibliography: Legend Bike Magazine: Volume 8. no. 80, May 1999, pages 42-43
Source: Hessink's NL
N.B. Another short article on this site indicates that nearly 10,000 of the 48N and 48NP machines were built and sold.