I have a 72 XS650 with an aftermarket Ascension Cycle Works charging system and a Pamco ignition. On occasion, when I use the electric start, my neutral light dims and the starter will not turn over the engine. When I check the voltage at the battery it reads under 12 volts. I try again, the starter engages, engine starts and I register 13.5 - 14.2 volts. If I shut the bike off, my battery reads 12+ volts. I have a Motobatt 160cc, 15.0ah gel battery that is less then 1 year old. When I rebuilt the engine 3 years ago, I completely overhauled the mechanical part of the starter system, including replacing the right hand side of the crankshaft that includes the machined starter gear and all other gears/shafts. My starter motor is original. Also I have noticed that when running at idle that my headlight dims and dims even more when the turn signals are actuated. It seems like a ground problem? I have checked and found no obvious problems. Could there be a problem in the ignition switch? Any help would be appreciated. Happy New Year.