Ducati Diavel Owner's Manual page 119

Rear brake pedal
(fig. 102)
E
7
loosen counter nut (7).
Turn pedal stroke adjusting screw (6) until pedal is in the
desired position.
Tighten the counter nut (7).
Operate the pedal by hand to check that there is 1.5 to 2 mm
6
of freeplay before the brake bites.
If not, adjust the length of the master cylinder pushrod as
follows.
Slacken off the counter nut (10) on the pushrod.
Screw the pushrod (8) into the front fork (9) to increase the
freeplay, or screw it out to reduce it.
Tighten the counter nut (10) and recheck the pedal freeplay.
10 9
8
fig. 102
118