Make the rear wheel turn until you find the position where chain is tightest. Set the vehicle on the side stand. Push down the chain at the point of measurement and release. Measure the distance between the "aperture" upper profile and pin centre.
The read distance must be: 9 to 11 mm.

Important
If the drive chain is too tight or too slack, adjust it so that tension reading will fall within specified range.
To adjust the tension remove the rear splash guard (sect. 7 - 13, Removal of the swingarm).
Slacken off the two clamp screws (1) that secure the rear wheel hub to the swingarm.
Fit the hook spanner code 88713.1038 Inserting its tooth in the eccentric hub (2).
Rotate the eccentric hub (2) to obtain the correct chain tension.
Turn counter clockwise to tighten the chain; clockwise to loosen (from chain side).
Important
An incorrectly tensioned chain will lead to accelerated wear of the transmission components.
If the screws (1) are removed, lubricate with specified grease underhead and thread, then tighten the screws (1) to the torque of 35 nm +/- 5% (sect. 3 - 3, Frame torque settings) proceeding with sequence 1-2-1.

Warning
The correct tightening of the fixing screws of the eccentric hub is essential for the safety of the rider and the passenger (sect. 3 - 3, Frame torque settings).
Refit the rear splash guard (sect. 7 - 13, Refitting the swingarm).
Adjusting the steering head bearings
Checking brake pad wear and changing brake padsRemoval of the timing gears
Slide out driving gear (a) of timing gear pair (13) and remove the woodruff
key (14).
Relieve the staking on the lock washer (12) of the nut (11).
Restrain the driven timing gear by inserting a pin in one of the holes, and
unscrew the nut (11).
Remove the nut (11), washer (12) ...
Replacing the rear phonic wheel sensor
Disconnect the rear abs sensor (5) connector (c) from the main electric
wiring.
Open all the retainer clamps of the rear abs sensor cable (5): refer to table of
sect. 7 - 6, Flexible wiring/hoses
positioning.
Remove the rear abs sensor (5) from its seat on the rear calliper mounting ...
Refitting the rear sprocket
Check the cush drive bushes (6) condition and, if necessary, replace them by
removing them from the flange.
Refitting is the reverse of removal.
Apply recommended grease on the rear sprocket flange (5) external diameter.
Place the rear sprocket flange (5) on sprocket (17) by inserting it ...