Ducati MONSTER 620 2002 Manuel D'utilisation page 120

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 mid-length of swingarm. The
lower portion of the chain should have a slack of 25- 27
mm (fig. 43).
To adjust chain tension, slacken the nut (1, fig. 44) of the
wheel spindle. Then tighten (clockwise) or slacken
E similarly the screw (2) 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.
48
25 ÷ 27 mm
2
fig. 43
1
fig. 44