Honda C8R600F4 Service Manual page 328

ELECTRIC STARTER
Check for continuity between pairs of commutator
bars.
There should be continuity.
Check for continuity between each commutator bar
and the armature shaft.
There should be no continuity.
Check for continuity between the insulated brush
and cable terminal.
There should be continuity.
Check for continuity between the cable terminal
and motor case.
There should be no continuity.