Engine: Single cylinder four-stroke OHV
Bore & stroke: 60 x 61 mm (2.4 x 2.4 inches)
Carburettor: Dell'Orto 22 mm
Compression ratio: 7.0:1
Engine Capacity: 172cc (10.51 cubic inches)
Ignition: Bobine, mechanically timed
Maximum power: 9.38 h.p. (6.9 kW) @ 6500 rpm
Valve train: OHV (Overhead Valves)
Valves per cylinder: 2
Cooling system: Air cooled
Lubrication: Wet sump forced circulation with mechanical gear pump
Transmission: Gear primary, chain final
Clutch: Cable operated with multiple wet disc in oil bath
Gearbox: 4-speed foot-change
Throttle: Cable operated
Frame type: Monotube beam frame
Front Suspension: Telescopic fork and shock absorbers
Rear Suspension: Oscillating horizontal single shock
Front tyre: 2.50 x 17"
Rear tyre: 2.50 x 17"
Front Brake: Drum, Ø160 mm
Rear Brake: Drum, Ø140 mm
Seat: Dual seat
Fuel tank capacity: 16 litre
Dry weight: 122 kg (269 pounds)
Top speed: 110 km/h (68.4 mph)
In 1956 Aermacchi released the Chimera (or Dream) 175cc motorcycle, designed by specialist Alfredo Bianchi and designer/pilot Mario Revelli di Beaumont, with its enclosed engine compartment and futuristic jet engine-like appearance. The small four-stroke 172.4cc displacement engines were mounted horizontally and used an OHV cylinder head. Fuelled by a 22mm Dell'Orto carburettor and fired by a Marelli magneto, the engine generated slightly more than 13 h.p. at 6,500 RPM. The Chimera used a four-speed transmission and chain drive to put the power to the 17 in. rear wheel. The front wheel was also 17 in. and both had drum brakes. The Chimera had telescopic front forks and a single rear shock to provide suspension for the rider. Total dry weight was 122 kg*.
The futuristic Chimera 175 was the star of the 1956 Milan motorcycle show. In the words of Revelli himself, it offered
But the accolades it earned from the press did not translate well into actual sales. Compared to other models of its day, the front mudguard looked like it was hanging out in space, about 6 inches too high for the front wheel. The company claimed it was designed this way to afford the suspension additional clearance in the event it was taken off-road.
However, Aermacchi continued to build the Chimera, despite poor sales, until 1961. It probably was too futuristic...
Notes. * different sources vary on all-up weight.
Source: Hessink's NL