Ducati MONSTER 821 Workshop Manual page 1031

Warning
If fitting a new primary driving gear, check the backlash.
To check the backlash, temporarily fit the clutch housing (1) complete with inner spacer (3), the driven gear
(2) and the inner race on the gearbox primary shaft.
Fix a dial gauge to the crankcase, positioning the stylus against a gear tooth.
Turn the driven gear (2) to mesh the teeth and check that backlash ranges between 0.05 and 0.07 mm.
Repeat the check at 16 different points of the driven gear.
If the measured values are outside the tolerance limits, try changing the position of driven gear (2) on the
primary shaft, leaving the driving gear (7) on the crankshaft in the same position.
If the backlash is still outside the tolerance limits, replace the complete primary drive gears: gear (2) and
gear (7).
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