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 canisterChecking and topping up coolant level
Check coolant level in the expansion tank on the right side of
the vehicle.
Steer the handlebar completely to the left and check that the
level is between the min and max marks on the side of the
expansion reservoir.
Top up if the level is below the min mark.
Unscrew the filler plug (1) ...
Refitting the lubrication system
Note
Before fitting the pipes (7), it is recommended to check the presence of
the o-rings (e). Lubricate them by using engine
oil.
If the nipples (5) have been removed from the radiator insert a washer (6) on
each nipple (5) and apply specific
threadlocker on threads on the radiator side ...
Cleaning and replacing the spark plugs
Spark plugs are essential to smooth engine running and
should be checked at regular intervals.
The condition of the spark plugs provides a good indication of
how well the engine is running.
Have the spark plugs inspected or replaced at a ducati dealer
or authorised service centre; they will ...