Remove the seat and turn it upside down.
Loosen the special screws (4), turn the plates (5) and open the seat cover (2) lateral sides to slide it out.

Removal of the seat
Reassembly of the seatReassembly of the crankcase halves
The crankcase halves must be in good condition and perfectly clean. The
mating surfaces must be perfectly flat and free
from burrs.
Overhauling the alternator-side crankcase half
The following parts must be present on the internal side of the crankcase
half:
Gearbox secondary shaft bearin ...
Reassembly of the connecting rods
Before starting, check that the crankshaft main bearing journals and big-end
journals are free of burrs or evident signs of
machining: if necessary, clean the surfaces with very fine emery cloth and oil.
Check that the grooves are in perfect condition with no signs of forcing.
Clean the cra ...
Removal of the exhaust system
Remove the silencer, as described in the paragraph "removing the silencer" of
this section.
Loosen the screws (28) and remove the exhaust by-pass valve cover (27).
Turn the exhaust valve pulley (a) to facilitate the throttle cable (25)
output.
Release the end fitting (b) of the cable ...