Before we wrap up the SuperSport story, there’s one last issue that needs to be addressed. Desmo. It’s a word bandied about by all of us armchair World Superbike Championship racers. Most of us actually have no idea what it means and think it is exclusive to Ducati. Shock and horror… it is not.
Mention of desmodromic valves (desmo) first seems to appear in 1896 within several patents lodged by one Gustav Mees. But commercial usage dates from around 1910, when it was used in marine applications. By the 1950s, Mercedes-Benz was all over the technology, utilising desmo in its straight-8 cylinder racing engines, most notably used in the 300SLR racing cars. Desmodromic valve actuation was popular as it stopped valve springs snapping or floating at high rpm. Desmo gets around these problems by using a second set of rocker arms and cam lobes to shut the valves directly. This means that regardless of engine revs, the opportunity for valve float is eliminated. So where’s the downside? Once again there’s a problem in the cost department. When compared to traditional valve operation set-ups, the additional machining and parts required make it a pricey affair. Add to this that the valve adjustment process is twice as complicated as a regular engine and we realise why, for the most part, the engineering world (other than Ducati) has moved away from it.
Is this a good thing or a bad thing? From a technical viewpoint I have no idea, but I can tell you that it makes me want a Ducati – and more specifically, a 900 SuperSport on a set of Borranis…