Motorcycle Repair: Votage gauge on my 89 Dresser, voltage gauge, singals

Question
I have a 1989 Harley Dresser.  When I turn on my indicators the voltage gauge starts jumping from 9 to 12 real fast (in sinc with the singals)... I just replaced my entire charging system and bought a installed a new voltage gauge.  Also, when I turn on the stereo (without the bike running) it jumps around too.  I think the gauge is reading wrong as my bike runs good and everything works fine.  The dancing needle on my voltage gauge is pretty annoying.  Any ideas?  As said, brand new gauge.  Thanks, you provide a great service to folks

Answer
Check the voltage at the battery and see if it jumps around from there. Then you can compare the voltage from the battery to the gage on the bike. Your wire connections on the gage might be loose. If that is not the problem check the wires for a short and if that is not the problem, then you probably have a bad gage
Good luck and happy riding
Mike