Engine number found + ...

[wesk]

Disconnect the battery ground cable.

Do you have a aux power (slave) receptacle on the right fender? If so where are it's two cables connected?

Disconnect the two heavy wires that share one post (one should be from the cowl battery and one from the voltage regulator harness.)(if you have a slave receptacle and if the cable from the Slave receptacle is also connected there then leave it there) from the switch on top of the starter and bolt them together. Insulate them with tape or something. Now turn the lights on. If the lights are bright buy a new switch for the starter. If they are still dim you have a loosed battery terminal, or a corroded terminal/cable/post or a bad battery.