Aermacchi Motorcycles

Today in Motorcycle History

Aermacchi Production Racers 250cc 350cc

NEW AND IMPROVED CYLINDER HEAD CASTING has much deeper finning and considerably more metal around the four holding down stud holes. This stops any heat distortion, and allows more support for both inlet and exhaust valve guides, and valve seats.

THE SPARKING PLUG has been repositioned and is now almost vertical. This new position creates an annular cavity for rapid propagation of the nucleus after ignition has taken place.

THE 30 mm INLET PORT AND THE 39 mm INLET VALVE HEAD have been designed to give maximum gas flow and flexibility of the valve head at high r.p.m.

REDESIGNED FIVE SPEED CLOSE RATIO GEAR BOX with larger pinions to accommodate increased power output.

COMPLETELY REDESIGNED DRY CLUTCH which now frees immediately and is much lighter to operate.

SPINE FRAME of Aermacchi Harley Davidson design, with forged swinging arm locating members and alloy engine plates, swinging arm rear suspension hydraulically damped.

CERIANI FORKS - Double hydraulically damped forks also incorporating a friction steering damper.

WHEELS AND BRAKES - 18 In. alloy rim with CERIANI 230 mm 4 leading shoe front brake and CERIANI 200 mm2 leading shoe rear brake.

WEIGHT - 210 lbs. without fairing.

PRICES — according to specification ordered.


Engine Ala D'Oro 248.3 cc 344 cc

Bore and stroke 72 mm x 61 mm 74 mm x 80 mm

Compression ratio 11.5:1 11.0:1

Maximum speed 128 m.p.h. 138 m.p.h. (250 cc) (350 cc)

Maximum Power 9.800 - 10,000 8,000 - 8,400 (250 cc) (350 cc)

Maximum safe r.p.m. 10,200 8,500

ENGINE/GEAR BOX UNIT CONSTRUCTION - Crankcases are of greatly improved design, incorporating a 34 pint oil reservoir. The latest models have only one oil pump, namely a feed pump, and use a gravity scavenge return system. Fully filtered oil is ensured by two special nylon filters. A further improvement is made to the camshaft oil feed, which is now controlled by small jets.

A VERY SPECIAL CON ROD with exceptional fatigue endurance is hand forged from solid CHROME NICKEL MOLYBDENUM of 85-97 tons per square inch tensile strength. It has the grain running longitudinally and large double strengthening webs around the big end eye and blended into the "H” section of the Rod. The small end of the rod being stiffened similarly.

THE SMALL FORGED FLY WHEELS with integral main shafts have a very substantial interference fit onto the large 30 mm crankpin, which has a copious oil reservoir. The double row 1 x ft in. rollers are located in a special high tensile light alloy cage located on the flanges of the crankpin and separately lubricated. The engine is now fitted with an outside flywheel which increases power and safe revs.

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