The front brake discs consist of an inner carrier, which is mounted to the wheel, and an outer rotor. Both parts must be changed together as a pair.
Remove the front wheel (sect. 7 - 1, Removal of the front wheel).
Undo the retaining screws (5) of the disc to the wheel, remove the disc (7) and, on its left side, slide out the phonic wheel (6).

Removal of the front brake system
Overhauling the front brake componentsRefuelling
Never overfill the tank when refuelling. The fuel level should
always be below the rim of the filler recess.
Warning
Use low-lead fuel with 95 octane rating at origin
minimum (see "top-ups" table, page 173).
Check that no fuel is trapped in the filler cap recess.
...
Checking the engine timing
Set the engine to the configuration described for the "checking and adjusting
the valve clearances", previously indicated.
Install tool 88765.1188 (G) in the spark plug bore to determine the piston tdc,
the gauges (h) on the tool 88765.1518
And the timing check tool (degree wheel (l) 887 ...
Refitting the abs control unit
If the brake hoses (7), (8), (9) and (10) on the abs control unit are changed
or removed, ensure that the fittings on the
control unit are positioned correctly.
Warning
If incorrectly positioned, the hose can affect brake operation and
foul moving parts. Position the hose as shown in the
fig ...