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 padsRefitting the cylinder head assemblies
Warning
To prevent oil leaks past the contact area between cylinders and
crankcase, each time the head is removed, cylinder and
piston must be removed as well to clean the mating faces of crankcase and
cylinder and restore the spoiled gaskets and
o-rings and apply again liquid sealant (sect. ...
Trip 1 meter
This function shows the distance travelled since the trip meter was last
reset (in km or miles depending on the specific
application).
Press and hold (1) "s" for 3 seconds while in this function to reset the trip
odometer.
When the reading exceeds 9999.9, Distance travelled is reset and t ...
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 ...