The Desmodromic valve system was designed and developed by Dr.
Fabio Taglioni.
A Desmodromic valve system is one where the engine valves are both opened and closed by a cam. Among the advantages of a desmo engine are that there are no heavy power robbing springs used to close the valves, better protection for the engine if it is over revved, and better performance and/or overall efficiency.
If in a racing application a normal valve spring engine had an upper rpm limit of about 10,000 rpm, that same engine design when equipped with a Desmodromic valve system would capable of 15,000 rpm, and much more power.
Ducati and Mercedes are two major companies who have used the Desmodromic system in racing engines. Currently only Ducati produces a production machine employing a Desmodromic valve system.
The disadvantage of the Desmodromic valve system is its complexity and cost. And while the overall efficiency possible in a Desmodromic design can not be achieved in current applications it’s main advantage, greater power output, can be achieved at less expense by using four or more valves per cylinder.