In a Desmo system, a mechanism controls both valve opening and closing. Closure is not left solely to a conventional valve spring. This allows the designer to control valve motion precisely with aggressive cam profiles and at high engine speeds.
Ducati introduced the principle in its 1956 125 GP Desmo racer, designed by Fabio Taglioni. That year, Gianni Degli Antoni rode it to victory in the Swedish Grand Prix at Hedemora, beginning a long association between the Desmo name and Ducati racing engineering.
A modern example is the Panigale V4’s Desmosedici Stradale engine, where four camshafts control 16 valves. Desmo identifies a particular valve-actuation solution, rather than engine capacity or cylinder count.