I have some stuff that may help when it come to checking the Alternator/Stator & the Regulator Rectifier.
The pic above shows that you can test the alternator from the wire that goes from the alternator to the wire harness. Unplug the connector from the wire harness and check it there. These pics are for a 90'-93' VFR, but the 400rr prolly has a similar system.
-Below is the factory way to test the Regulator Rectifier
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The pics above show the factory way to test the RR. But this test will show that your RR is faulty if you use certain multimeters. I use a Craftsman multimeter and it would never do the above test properly (I think that the battery operated multimeters dont put out enough current.?.). But a better way to test your RR is at that electrex site that Scotteq posted. Its called the diodes test. There is a link to it on the right of the page at electrex.