I have a 2007 classic that has a good battery-has been tested. Problem with the bike is when riding the bike will go from 12 to 16 volts on the gauge. It doesn't do it all the time, i checked battery and had good volts at idle the bike is putting out 12.3/12.4 and at 3,000 rpms is putting out 13.9 average. I looked in my service book but i dont see how to test the regulator and stator with the three phase charging system. Any help is appricated and the bike has 27k on it.

 

any reading higher than 14.8 at the battery with a "real" voltmeter indicates a bad voltage regulator.

test at the battery.

mike

 

I agree with Mike, any Voltage reading above 14.8 means the Voltage reg. isn't doing it's job.

If you want to check the stator:
Stator testing
Turn the bike off and disconnect the Stator from the Voltage Regulator.
The end of the connector from the stator has 3 sockets. Set your meter to ohms and connect one lead to the battery negative. With the other lead make contact with the conductors inside each socket. You are checking for a grounded wire, each socket should show an open circuit to ground, no continuity.
Now take both meter leads and check resistance between each of the three sockets, 1-2, 2-3 and 1-3. The resistance should be 0.1 – 0.3 ohm.
Next check the Stator’s AC output. Set the meter to ACV 100V scale. With the Stator unplugged from the VR and the bike in neutral, start the bike. Run the bike at 2,000 rpm and check the Stator output between sockets 1-2, 2-3 and 1-3. The voltage should read approximately 32-46 Volts AC.

Approximate Spec’s:
22 amp system 19 – 26 V AC per 1,000 rpm
32 amp system 16 – 20 V AC per 1,000 rpm
45 amp system 19 – 26 V AC per 1,000 rpm

 

thanks for the info turned out stator was grounding out

 

Just went through the same thing. Voltage would fluctuate. Turned out one phase of the stator was fried. I was told that when the stator goes it's unusual for the voltage to fluctuate. Perhaps it fluctuated as the stator was in the process of dying. Eventually the fluctuation stopped, probably a sign it finally fried.

 

It may be wise to replace the Voltage Regulator too. A bad Stator can take out the V R.
Here are a couple things from the electrical diagnostic manual.