Motorcycle Repair: 83 honda nighthawk electrical probs, grit sandpaper, stator coil

Question
I recently purchased a 1983 nighthawk 550 with 35k miles. It has trouble starting and charging the battery. The battery is fairly new, although it was purchased by the previous owner. I've tested the battery with a cheap voltmeter and when the bike is running the battery loses its charge (from 12v when I fully charge it, to a lot less after idling the bike for 10-15 minutes). I suspect the alternator, but could something else in the charging system be causing the problem? Also, the bike does not start normally by pressing the start button; the starter solenoid "clicks" but the starter itself doesnt turn the motor. The engine will start when I bypass the starter solenoid and directly connect the starter with the battery. As you can see, the bike has several electrical problems, and I'm planning on going over the entire electrical system soon (both front and back turn signals are missing), but I wanted to see if you could help me pinpoint some of the problems before I do. Thanks, and let me know if you need any more information.  

Answer
Hi Matt.
 It sounds like you have a couple of problems there.

1)  Look for shorts in the starter circuit and remove and inspect the contacts in the starter motor.  You may need to clean them with a little thousand grit sandpaper.  When the contacts are shiney, they will work.

2)  The charging system is the other problem.  Check the battery with a hygrometer.  That will tell you if all of the cells in the battery are bad.  If you have any bad cells in the battery are bad, then so is the battery and it will not hold a charge.

2a)  To test the stator coil, start the bike and put your multimeter leads on the battery terminals.  You should see 13-15 VDC on the meter.  Anything less and the stator is bad.  Replace it.

 Based on your description, it sounds like the stator is bad, but test it again, and check the battery with a hygrometer before replacing anything.

 Regulator/rectifiers can go bad, but you stand a better chance of being hit by lightning than that happening.

Let me know what happens.
Good luck.
FALCON