Ducati MONSTER 821 Workshop Manual page 873

Check the tensioning value and adjust the vertical head belt (5) and horizontal head belt (6), if necessary.
Check the tensioning values on belt (5) section (I) and belt (6) section (L).
After reaching the required tension, make sure that nut (4) retaining the mobile tensioner (2) is tightened
to 25 Nm (Min. 22 Nm - Max. 28 Nm) and vertical head screws (1) to 10 Nm (Min. 9 Nm - Max. 11 Nm).
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