Motorcycle Repair: 2004 Sportster 1200 electrical problems, harley shop, stator

Question
Hello, I recently took my sportster on a road trip and the first time we stopped the battery did not have enough juice to turn the bike over. The battery is within one year old and I keep it on a float charger all the time. We run-started the bike and kept going....bad idea. The problem kept getting worse and the battery light finally came on and the speedometer started going crazy going up and down, the bike finally cut off. I talked to a Harley shop and he said something about a regulator, does that sound correct? I'm just wanting to know how to diagnose and fix the problem myself. Thanks so much.

Answer
Its either the regulator or the stator. You would have to test the stator to see what the problem is. Charge the battery fully and at the battery see what voltage the bike is making at around 2000 RPM. If its less than 13.5 then you next need to test the stator. Unplug the regulator and at the pins for the stator go pin to ground with a OHM meter, then do the other pin. If you have OHMs then the stator is bad. If it passes then start the bike and at the pins for the stator see what the AC voltage is. At 2000 it should be around 60 volts. If not then the stator is bad and needs replaced. If it passes then the regulator is bad and needs replaced
Good luck and happy riding
Mike