Ducati MONSTER Manuel De L'utilisateur page 110

Chain tensioning
Turn the rear wheel slowly until you find the position
where chain tension is highest.
With the motorcycle on the side stand, push the chain up
pressing with a finger at the point where it intersects
with swing arm centerline. The lower portion of the chain
should have a slack as follows (fig. 33.1):
20-25 mm (600/750);
25-30 mm (900).
E To adjust chain tension, slacken the nut (1, fig. 33.2) of
the wheel spindle. Then tighten similarly the screw (2)
clockwise on both sides of the swing arm to increase or
reduce chain tension. If you are slackening the chain, you
will have to push the wheel forward.
Important
Improper chain tension will lead to early wear of
transmission parts.
Make sure you have adjusted to the same setting marks
on both sides of the swing arm. This will ensure perfect
wheel alignment.
Grease threading of wheel spindle nut (1) with SHELL
Retinax HDX2 and torque up to 72 Nm.
Grease threading of adjuster screws (2) with SHELL
Alvania R3 and torque up to 8 Nm.
42
20÷25 mm (600/750)
25÷30 mm (900)
fig. 33.1
fig. 33.2