How Pneumatic Valves Work in MotoGP [Video]
The biggest problem for the valve train of a MotoGP bike is the high rpm. As Guidotti says, for the bikes he's taking care of, power increased 5-8% with each 1,000 rpm at the top, so it's fairly easy to understand why so many engine manufacturers and mechanics are considering aiming higher.
Problem is, the springs which control the valves are no longer capable to keep up with the high rpm and will eventually break, causing a massive engine failure. It's their inherent constructive nature which imposes certain limits and there's nothing mechanics can do to change this. This is where pneumatic valves come into the equation.
With high-pressure air moving the valves up and down and way less moving parts, the engine rpm can go to more than 20,000, even though Guidotti says Avintia bikes only work in the 15k range. Air is compressed to 200 bar (2,900 psi) and is stored in a special canister.
From this recipient, it passes into a regulator, which operates at a slightly lower pressure of "just" 170 bar (2,465 psi) and which keeps pressure in the cylinder heads to about 10 bar (145 psi). Basically, this is the operation pressure of Avintia's pneumatic valve train.
Now, air will also leak, so pressure is constantly monitored, usually after each hour of operation. When the pressure in the regulator drops, it is brought back to specs using the 200-bar canister. The dash shows the static and running pressures and alerts when one of the figures go near the critical level.
The pneumatic valves increase the upper mid-range and top-end power, and also require longer gearing and carefully-trimmed fuel mappings.