The negative cable, which is normally connected to the negative pole of the battery, is fastened to the crankcase. From here, the cable branches off and splits up within the electrical system to carry the ground connection to the different elements in the system.

The image shows the ground connection on left side of the engine crankcase.
The battery charging circuit and power distribution
Electrical power for lighting and signalling devicesLimitations
This emission control system warranty shall not cover any
of the following:
Repair or replacement required as a result of
Accident,
Misuse,
Repairs improperly performed or replacements improperly
installed,
Use of replacement parts or accessories not conforming
to ducati specifi ...
Overhaul of the crankcase halves
Carefully examine the engine crankcase halves.
Check that the surfaces of the crankcase halves are perfectly flat using a
reference surface.
Check that the bearings (1) and (18), and the bushings (2) and (17) are in
optimum conditions. Note that the main
bearings must always be changed in p ...
Steering head: steering
Screw
Steering head
Screw
Lower rh u-bolt
Lower lh u-bolt
Bearing
Screw
Sealing ring
Washer
Spacer
Washer
Nut
Washer
Screw
Bottom yoke
Dowel
Nut
Screw
Special screw
Clip nut
Left-hand support
Front splashguard
Right-hand support
Front support
S ...