Ducati XDIAVEL Owner's Manual page 264

Rear brake pedal
Loosen lock nut (4).
Turn pedal stroke adjusting screw (5) until pedal is in
the desired position.
Tighten the lock nut (4).
Operate the pedal by hand to check that there is 3 ÷
6 mm of free play before the brake bites.
If not, adjust the length of the master cylinder control
rod as follows:
Loosen lock nut (6) on master cylinder rod.
Screw the rod (7) into the fork (8) to decrease the free
play, or screw it out to increase it.
Tighten lock nut (6) and check play again.
8 6 7
5
4
Fig. 181
263