Ask The Editors: What is Desmodromic?

Duc and desmo go hand in hand.

Absolutely. Desmo is short for desmodromic or desmodromic valve. Essentially it foregoes the common method of relying upon a spring to open and close the valves and instead relies upon a mechanism to accomplish this task. In Ducat’s case, the desmodromic method they employ uses a pair of cam lobes – one to push the valve open and the other to pull it closed.

The advantage to such a system is that it usually lasts longer between service intervals than a comparable spring. It also allows for more precise control over the valve timing. Plus the valves themselves are less prone to damage from imprecise actuation (think valve lash).

There are some downsides too, though. It means a few more moving parts in the valvetrain that could potentially fail over time. Additionally desmodromic designs typically apply more force to the system, which often means greater friction and higher operating temperatures.

Ducati’s claims that the system allows the valvetrain to cycle faster and thus higher RPMs in action is tough to dispute given the company’s reputation for performance both on and off the racetrack. We’re always of two minds when it comes to integrating this type of technology into the off-road environment, however, because while it works – the idea of being able to rebuild and tune our machines in the backyard with standard tools gets further out of reach with each such advancement.

However, and like we stated in the article you referenced, we probably need not become overly concerned. It’s very unlikely Ducati (or Triumph) are going to develop ATV variants of these new 450s on account of the reasons we discussed here.

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