Carruthers. The following year Carruthers competed at the Isle of Man TT. A new era began in 1971 with the development of twin-cylinder two-stroke racers of 250cc and 350cc capacity, designed at Aermacchi by their chief engineer, Ing. William Soncini. The first 250cc racer was very fast, with 46hp at 11,000rpm, and weighed only 250lbs. After Harley-Davidson acquired 100% of Aermacchi in 1972, they funded further racing development at the Aermacchi factory, and the racers were branded with Harley-Davidson on their fuel tanks. These two-stroke twins provided Harley-Davidson with their only Grand Prix wins, and four World Championships: 250cc World Championship in 1974, '75, and '76, and the 350cc World Championship in 1976, all under rider Walter Villa. List of Motorcycle Models (incomplete) 250 Cross 350 500 Linto Ala Azzura Ala Bianca Ala d'Oro (Golden Wing) [1958-1961] Ala Rossa Ala Verde Biccindrico Chimera Convrtible Corsaro Drixton Monsone Sprint 250 Sprint 350 Wisconsin 250 Zeffiro See also List of Italian companies Harley-Davidson Baja 100 off-road motorcycle References External links Leonardo website Italian brands Defunct aircraft manufacturers of Italy Defunct motorcycle manufacturers of Italy Vehicle manufacturing companies established in 1913 Italian companies established in 1913 Defunct manufacturing companies of Italy Alenia Aermacchi Leonardo S.p.A. Vehicle manufacturing companies disestablished in 2003 Italian companies disestablished in 2003