Short explanation of the word desmodromic
But what is this DESMO engine of DUCATI's
BUT WHAT IS THIS DUCATI ‘DESMO’ ENGINE?!
Desmo indicates a particular type of engine timing system; the DESMODROME system. Derived from the Greek DESMOS=drive and DROMOS=stroke. It refers to the controlled valve stroke in both directions.
The desmodromic system was born well before Ducati in the late 1800s. In the early 1950s, the Mercedes Benz car manufacturer used it on its multi-win formula 1 racing cars. The refinement and massive use of this system in motorcycling came about thanks to a famous Ducati engineer: Fabio Taglioni. As early as 1956, this system began to equip DUCATI motorbikes up to the present day, including Superbike and MotoGP bikes, becoming an authentic icon of the Borgo Panigale brand. Other motorbike manufacturers (Honda and BMW) tried to adopt this system, but with poor results.
In the desmodromic timing system of 4-stroke engines, unlike the one normally used on all engines, the spring responsible for the valve retraction with consequent closure of the cylinder is eliminated. Instead, a more complex mechanism is used in which the two rocker arms are controlled by a camshaft that has a complementary cam in addition to the normal cam. The valve is thus controlled in both opening and closing directly from the shaft.
But what are the advantages of a desmodromic system over a spring system?
Higher revs, engine revs, compared to spring-loaded engines, which at high revs tend to be inaccurate in closing the valves, sometimes causing overspeeds.
Energy savings due to easier rocker arm actuation compared to continuous spring compression.
Higher performance due to the possibility of running the engine at higher revs and with less friction, thanks to which losses at medium and low revs will be reduced.
In addition, with the desmodromic system there will be greater acceleration of the valve in both the closing and opening phases, allowing an extension of fluid transit times.
Unfortunately, there are also disadvantages of the desmo system.
The main one is due to the high design and manufacturing costs compared to traditional systems. The necessary compliance with extremely precise tolerances and machining lead to an inevitable increase in costs. This is why today the desmodromic system is not very widespread and its mass production is only carried out by DUCATI, which uses this type of timing system in all its engine production (Multistrada V4 excluded).
The countless world title victories in both Superbike and MotoGP prove that DUCATI machines powered by V2 and V4 engines with the desmo system have been and still remain among the most powerful bikes in the world.
Numerous books have been written on the desmodromic system, and we do not want to and cannot replace much more competent authors than ourselves. With this short article, we wanted to briefly and very simplistically explain the word ‘DESMO’, which is often used but whose meaning is not always known. What is certain is that this word is now inextricably linked to the name ‘DUCATI’.
When you rent a DUCATI motorbike at our company MMR22 in Majorca, you can say that the DUCATI EXPERIENCE IN MALLORCA also includes a test of the famous DESMODROMICO valve management system.