For Ducati, the V4 layout at 90° is the utmost expression of sportiness for a motorcycle engine. It is no coincidence that it is the same solution used in the MotoGP Desmosedici engines. The 90° V layout of the cylinders creates a natural balancing of first-order forces without the need to resort to a balance shaft to eliminate the vibrations that notoriously entail increases in weight and power absorption. In addition to this primary benefit, which is extremely important for the reliability and mechanical efficiency of an engine that reaches rotation speeds greater than 14,000 rpm, there are others that make the configuration chosen by Ducati the most technically refined.
On street bikes the crankshaft rotates in the same direction as the wheels. In contrast, in MotoGP the counter-rotating crankshaft that rotates in the opposite direction is commonly used. The Desmosedici Stradale borrowed this technical solution from MotoGP. This innovative solution makes it possible to compensate for part of the gyroscopic effect produced by the wheels, making the bike more agile and precise when changing directions. The counter-rotating crankshaft also generates a torque due to inertia that tends to lower the front end during acceleration, and the rear end when braking, thus reducing the wheelie phenomenon.
"Twin Pulse" firing order
The crank pins, offset by 70° like on the Desmosedici GP, require a "Twin Pulse" firing order to generate power that is easy to handle and optimise traction when coming out of curves ("Big Bang" effect). Thanks to this firing order the Desmosedici Stradale makes a unique and distinctive sound.
On the Desmosedici Stradale the design of the desmodromic system is a key factor for obtaining top performance. The Desmodromic system in the Desmosedici Stradale uses components that have been completely redesigned and miniaturised to obtain very compact heads, achieving a level of sophistication, compactness and lightness never seen before on a Ducati bike. Each component of the system was designed and tested to safely reach the rotation speeds the V4 is capable of achieving. Also contributing to the compact engine heads are the new spark plugs, smaller than the standard model currently in production. The four camshafts of the Desmosedici Stradale engine move the 16 steel valves, the intake valves having a diameter of 34 mm and the exhaust valves measuring 27.5 mm in diameter, quite large in relation to the 81 mm bore adopted. The valve seats are made of sintered steel. Given the V4's high rotation speeds and the large size of the valves, the latter could not follow the cam closure profiles using a traditional spring system. This is why the Desmodromic system becomes indispensable. In Ducati's ""Desmo"" the valves are mechanically closed with an accuracy similar to that of the opening phase, making it possible to realise more pronounced cam profiles and extreme timing that optimise the dynamic flow of fluids both during intake and exhaust and therefore greater performance of the engine. The camshafts are controlled by two “silent” timing chains. On the front timing system the chain drives the intake camshaft, which in turn transmits motion to the exhaust via a pair of gear wheels (mixed chain-gear timing system). On the rear timing system, on the other hand, the chain drives the exhaust shaft which transmits motion to the intake line. This choice minimises timing absorption, benefiting performance and reliability. The chain that controls the timing of the front cylinders is positioned on the right side of the engine and is driven by the crankshaft through a gear on the sprocket of the primary transmission. The one that drives the rear cylinders is situated on the left side of the engine and is driven by a gear that is part of the crankshaft. Each head has an ""anti-beat"" sensor that makes it possible to optimise the management of advance firing, avoiding knocking phenomena