Ducati MONSTER 821 Workshop Manual page 1138

At each overhaul it is recommended to also replace the sealing ring (22) positioned between gearbox
primary shaft support bearing (20) and chain-side crankcase half (12).
Upon assembling, lubricate ring (22) with KLÜBERPLUS S 06/100 (or denatured alcohol), then drive it fully
home inside crankcase half and aim it as shown.
Check ring positioning value. It must be:
oil seal height (B) 4 ± 0.2 mm;
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oil seal positioning (C) 67 ± 0.2 mm;
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(D) 5.0 ÷ 5.02 mm;
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(E) 66.0 ÷ 66.05 mm.
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