I suspect the harness being at fault here. Two regulators that fail on the same bike...unlikely. Start by checking the 2-pin connector that is right under the seat. If the red wire / connector fails, you get no juice to the battery. The rectifier/regulator may work, but the battery gets no charge. Do this as a first step, there are other things to check, but later.

(NO charge at all? Please verify this. Connect a voltmeter to the battery terminals, start the engine.
At idle, you should see 13,4-13,5 V DC. When increasing the revs, the charge voltage drops to 12-12,5V DC. )

adam and hayley wrote on 06/09/14 at 22:34:52:


I had an '87 and could not keep the battery charged on short trips, just puttering around town, if I made a 70 mile round trip I had no problems. I changed the rectifier, checked the wiring and "determined" the stator was indeed weak, charging some but not enough for those short trips. I got a battery tender and hooked it up once a week or so and that solved my problem, it was ALOT cheaper than a stator.  Just my 2 cents worth.

Did you tell the mechanic it wasn't charging, or did he or you put a meter on it. Extra accessories or a bad battery cable or a shorted cell can cause the same symptoms.

Start with the basics mentioned - VERIFY that you have - or don´t have - a charging voltage. Verify that that connector is OK. Your battery could be bad, but you need to verify what comes out of the regulator first. Then, proceed the faultfinding if necessary, but step by step, like checking what goes IN to the regulator.

Just forget the stator talk for now. It just adds to the confusion. (They don´t break THAT often. I have a 1953 Triumph engine that finally needed a new one, but that´s because of gross maltreatment)

Report back on your volt meter readings at idle and at 2000 rpm (it will take a few secs for the voltage to stabilize, so keep the engine at the same rpm for some 10 secs).