Inspecting The Fork Selector Drum - Ducati MONSTER 821 Workshop Manual

Inspecting the fork selector drum

Use a gauge to measure the clearance between fork pin and the groove on the selector drum.
If the service limit has been exceeded, determine which part must be replaced by comparing these
dimensions with those of new components.
Also check the wear on the drum support pins; these must not show any signs of scoring, burrs, or
deformation.
Turn the drum in the crankcase to establish the extent of radial play.
If play is excessive, change whichever part is most worn.
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