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 canisterHands free
Hands free
Special screw
Plug
Electric fuel plug
Button
Spring
Frame
Elastic pin
Spare parts catalogue
Diavel abs handlebar and controls
Diavel carbon
abs
handlebar and controls
Important
Bold reference numbers in this section identify parts not shown in the
figures a ...
Checking valve lift
Set the engine to the configuration described for the "checking and adjusting
the valve clearances", previously indicated.
Position the tool 88765.1518 On the cylinder head: the part marked "a" should be
on the intake side and the part
marked "s" should be on the exhaust side.
Seat the pl ...
Steering angle adjustment
Loosen the nuts (17) and adjuster screws (16) on both sides of the bottom
yoke.
Use a 6 to 6.5 Mm spacer (a) fitted to the fork outer tube, or use a gauge.
Turn the front forks to the right until the spacer (a) is seated against the
frame top tube.
Tighten the adjuster screw (16) to ...