[1][2] Tonti's first job was at Benelli, where he worked on a road-racing supercharged four, and then after World War II he went to Aermacchi.
Mondial, and helped break MV Agusta's Moto GP dominance of lightweight Grand Prix motorcycle racing in that year.
[3] After Mondial made a secret deal with Gilera, Moto Guzzi, and MV Agusta to stop racing at the end of 1957, Tonti went to Bianchi where he designed 250 cc four-stroke twins.
In the 1970s, Tonti helped his longtime friend Reno Leoni in his efforts to fit Ducati fork dampers in the Moto Guzzi racer he was campaigning in American AMA Superbike racing.
It was a six-speed pushrod straight-twin engine using the cylinders and heads from Aermacchi's horizontal single DS racer, combined with a new crankcase.