Total Motorcycle Website – 2005 Ducati 999R Exclusive – Page 2

New cylinder assemblies

In order to improve performance, the cylinder heads and pistons have been completely redesigned and should really be regarded as completely new components, designed specifically for racing. The pistons are forged and constructed from an aluminium alloy with high mechanical specifications to ensure outstanding geometrical stability during the wide thermal excursions to which they are subject. The variation of the geometrical specification, as well as the new shape of the combustion cavity in the head, has resulted in a compression ratio of 12.45 +/- 0.5 :1 (slightly greater than that of the previous R version of the Testastretta engine, which was rated at 12.3:1).

The valve seats are deeper due to the increased valve lifts. The heads have undergone a radical fluid-dynamics redesign. In order to make it possible to use larger diameter valves, their centre distances have been increased which means that the routing and dimensions of the intake and exhaust ducts have also had to be modified.

Still in comparison to the previous 999R Testastretta, the squish surfaces have been increased to improve the turbulent flow in the combustion chamber, resulting in significantly increased combustion efficiency. To summarise, the improvements to the new 999R engine’s cylinders have greatly increased the engine’s ability to “breathe” as well as its combustion output. The result of these modifications is evident from the significant improvements in overall performance of the road version, which means with absolutely standard exhaust system, silencer and intake system. The engine also meets established emissions standards. It should be noted that metal gaskets are not used between the head and cylinder of each assembly, but rather special seal rings (called Wills seals) around the perimeter of the combustion chamber. The large cylinder bore makes this necessary if a perfect seal is to be achieved. The overall redesign of the cylinder head has also made it necessary to respecify the cooling ducts. The valve covers are now in magnesium for lower weight.

Timing belts

To limit the temperature of the timing belts and not only to keep down the overall weight of the vehicle, Ducati’s competition bikes have never been fitted with protective timing belt covers. However these units are necessary to protect the belts when the bike runs onto the gravel at the side of the track, and this year the Ducati R&D department has installed timing belt covers with dynamic cooling on the 999R, as already done on the 749R. The horizontal cylinder timing belt cover has an intake with a small sponge filter which attaches to the front fairing. The air is taken in at this point, circulates in the timing belt housing and exits via a NACA opening in the top of the vertical cylinder timing system cover.

The engine speed and phase timing wheel

A new element is the timing wheel on the timing drive shaft gear which, along with an magnetic induction sensor, generates the signal used by the ECU to detect the engine speed and operational phase. The timing gear teeth are not used, as on previous Testastretta engines, but instead the system uses a timing wheel with bumps machined onto the outer circumference of the gear face itself. This results in a cleaner electrical signal from the induction sensor.

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