Introduction; Operation - Ducati Scrambler Valve Measurement And Adjustment User Manual

Introduction

Bringing the valve clearances into factory specifications assures the best possible
performance of from your scrambler.

Operation

The Desmodromic (Desmo) engines use a positive valve control system to open and
close the valves at the same time in the combustion cycle regardless of RPM. The
Desmo valve system uses an opening rocker arm and a closing rocker arm that
press on shims attached to the valve stem to open and close the valve in a precisely
controlled manner: as the components wear, the gap (clearance) between the
rocker and the shim changes. To compensate for these naturally occurring changes,
the shims are replaced with thicker/thinner shims to bring the gap back into
specification.
The Scrambler engine is an updated version of
Ducati's classic SOHC V-twin. It is an air-and-oil
cooled two-valve engine displacing 803cc. The
valve service intervals are more frequent with the
air/oil cooled engines; therefore the Scrambler
Valve Adjustment Intervals are 7500 miles.
The shims don't wear as much as the valve seats
do. As the engine is run, the face of the valves
and seats wear as they bed into each other
(opener clearances get smaller and the closer
clearances get bigger). The result is opening and
closing clearances that change with use.
1. Valve
2. Closing Shim
3. Closing Rocker Arm
4. Retaining Clip
5. Opening Rocker Arm
6. Opening Shim
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