Position seal (18) in tank cap (10) as shown and reassemble following the removal procedure in the reverse sequence.

In particular tighten the screws (17) to a torque of 3 nm +/- 10% (sect. 3 - 3, Frame torque settings).

Removal of the fuel tank filler cap
Replacing the tank flange and fuel sensorRemoving outer components
Note
The following removal operations are required in order to renew and/or
clean the crankcase halves. If the original
crankcase halves are to be reused, then the removal of these components is not
essential.
Unscrew the screw (17) and remove the oil breather valve (1) with the o-rings
...
Refitting the front sprocket
Grease the o-ring (16) and install it on the front sprocket spacer (15).
Fit the spacer, from the o-ring side, on the secondary shaft and drive it fully
home against the inner ring of the bearing.
Check that the splines of the gearbox secondary shaft and the sprocket are in
perfect condi ...
Removal of the fuel tank filler cap
Remove tank covers (sect. 5 - 2, Removal of the fuel tank fairings).
Remove hoses (8) and (15) from the filler cap assembly (10).
Open the filler cap.
Unscrew the outer screws (17) securing the ring nut to the filler cap recess.
Remove the filler cap assembly (10).
...