At age 22, Adalberto Garelli received a degree in engineering and dedicated his work to developing and perfecting the 2-stroke engine for Fiat. Garelli quit in 1911 due to Fiat's lack of enthusiasm for the 2-stroke engine. He continued his own engine design between 1911 and 1914 which resulted in the 350cc split-single. Garelli worked for other motorcycle manufacturers from 1914 to 1918 during which time he won a competition organized by the Italian Army to design a motorcycle with which he used his 350cc split-single engine.
After WWI Garelli began to produce motorcycles in his own factory. The Garelli 350cc split-single stayed in production until 1926 and made a major impact in racing. By 1928 his motorcycle interest was waning and his factory began producing military equipment leaving motorcycle production completely.