Aermacchi saw a GP renaissance in the ’70s with their 250 racers

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The name ‘Aermacchi’ tends to bring to mind their famous four-stroke horizontal single (or if you are of a different bent, their fabulous Schnieder Cup racing floatplanes). Two-stroke Grand Prix bikes, not so much.

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Aermacchi aren’t a name commonly associated with GP racing

Add the name ‘Harley-Davidson’ to the mix and you really are in strange territory. However in the mid ‘70s the company dominated the 250 class with three consecutive championships (plus one in the 350 class)!

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In the ’70s the brand did however put in a very strong showing in the 250s

Work was started on a two-stroke 250 in 1971 using the company’s Ala d’Oro 125 single as the basis. The air-cooled twin used a traditional piston port design.

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A 250 was developed from the brand’s Ala d’Oro 125 single

Renzo Pasolini was the factory rider and in the 1972 season finished second to Jarno Saarinen by a single point, winning three races in the process. On a bored and stroked 350cc version he finished third to Agostini and Saarinen in the larger class. The 250 was good for 50hp and weighed 108kg.

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Renzo Pasolini would race the 250 in 1972

After Pasolini’s death at Monza in ’73, Walter Villa took over riding duties for 1974 and proceeded to win the ’74, ’75 and ’76 250 championships, not to mention the ’76 350 championship.

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Walter Villa later took the 250s to three titles

The factory bikes received water-cooling in ’73, with privateer bikes following in ’74. Also in ’73 the bikes became known as ‘Aermacchi Harley-Davidson’ RR250/350s.

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1973 would see the bike’s branded ‘Aermacchi Harley-Davidson’

Development continued with Bimota frames appearing in ’77 and a rotary-valve motor in ’78, although HD sold its interest in Aermacchi to Cagiva before the new motor saw action. Cagiva continued to campaign both the 250 and 350 with Marco Luchinelli as their rider.

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Harley later sold their interest to Cagiva, who continued to campaign the 250s and 350s

This bike was bought directly from the factory in 1976 by Spanish rider Jose Maria Mallol and raced in the domestic championship that year before being sold to José Benaigues, who in turn sold it to its present owner. Power was 58hp at 12,000rpm, with the bike boasting a top speed of 250km/h.

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58hp propelled this machine to up to 250km/h

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A 500cc twin was also developed from the 250, beginning in 1973. Development was shelved for two years after Pasolini’s death but in ’75 the now water-cooled motor was installed in a Bimota frame.

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A 500cc twin variant was also produced in limited quantities

Of particular note was the use of four carburettors from the outset of the project. Output was 90hp at 9,000rpm and weight 127kg, offering a top speed of 280km/h. Another interesting feature were the twin front discs, which were gear driven to rotate in the opposite direction to the wheel. Only four 500s were built (this one was photographed in the Barber Museum) making them a very rare steed.

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Gear driven rotors counter-rotated to the wheel

And for those wondering at the floatplane reference…


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