Usa models are equipped with an additional system with an evaporative emissions canister that prevents fuel fumes from being discharged into the atmosphere.
The breather hose (4) is connected to the canister filter (1); when the fuel has been filtered, it is returned through the hose (2) to the horizontal (a) and vertical (b) intake manifolds via the hoses (2a) and (2b). Drainage pipe (c) and the hose (5) vent to the ground.
For correct positioning of the connection hoses consult the indications given below.

Evaporative emissions canister
Removal of the evaporative emissions canisterRemoving the silencer
Loosen the clamp (38) that retains the silencer (4) to the complete exhaust
system.
While holding the nut (8), loosen the screw (1) and remove the silencer (4)
from the motorcycle.
Loosen the screws (40) and remove the silencer guard (41).
...
Ducati limited warranty on emission control system
Ducati north america, inc., 10443 Bandley drive cupertino,
california, 95014 warrants that each new 1998 and later
ducati motorcycle, that includes as standard equipment a
headlight, tail-light and stoplight, and is street legal:
a) is designed, built and equipped so as to conform at the
time o ...
Charging the battery
Before charging the battery, it is recommended to remove it
from the motorcycle.
Important
The battery is housed in the cowling, always contact
a ducati dealer or an authorised service centre for its
removal.
Remove the left cowling (1, fig. 137) Loosening:
side screw (2, fig. 137) Retaining ...