It is possible to troubleshoot a faulty generator without removing the generator from the engine, or if necessary to remove it, without completely diassembling the generator. When a generator stops charging or not charging at a satisfactory rate as evidenced by a dead battery or signal light on switch panel remaining lighted, it is recommended that unless the trouble is known definitely, the following checking sequence should be used:
On installations employing a fuse in the generator field circuit, remove fuse at regulator and examine it to see if it has blown. When replacing fuse be sure insulating sleeve is in good condition and covers fuse properly.
Make certain the generator signal light circuit is not grounded. Remove the wire or wires from the generator "A" terminal and position so contact is not made with motorcycle. Turn ignition on. If generator light on instrument panel goes on, light circuit is grounded and may be reason for the generator not charging. If this circuit is grounded this condition must be corrected. If the generator signal light circuit tested OK or if a grounded condition has been corrected, proceed to testing generator output.
Testing generator output:
Remove wire from "F" terminal of generator. Connect a short jumper wire from generator "F" terminal to ground on motorcycle. Remove wire or wires from generator "A" terminal and connect the positive lead of a 0-30 ampere ammeter. Start engine and run at speed of 2000 RPM then momentarily connect negative lead of ammeter to motorcycle battery positive terminal (battery should be known to be good). If the ammeter reads 15 amps or more for a 6 volt generator or 10 amps or more for a 12 volt generator, then the generator is not at fault. Therefore, the difficulty is in the regulator or wiring circuit. If the generator shows no charge or charge below the minimum rate, it must be removed for further checking.
Important - Avoid running with generator field grounded for extended periods. Disconnect ammeter lead from battery before stopping engine to avoid discharging battery through generator.
Caution - it is advisable to flash field coils whenever wires have been removed from generator or regulator; or after generator or battery has been removed and is reinstalled. This is done to make sure generator has correct polarity. If polarity of generator is reversed, relay points will vibrate and burn. Flash field coils by momentarily touching a jumper wire between the "BAT" and "GEN" terminals on the regulator, after all wires have been properly connected and before starting engine. The momentary surge of current from battery to generator will correctly polarize generator.
If you need details on how to test a generator after it has been removed from the bike, email me and I'll get it to you.
1962 HD Service Manual pg. 5E-1