This is my first time working on a Harley, with its stator/rotor and rectifier/regulator. My Air Force daughter left me this Harley to keep up for her when she was deployed. It has less than 2K miles on it, and looks brand new. It has begun running on total battery discharge, and gets about 8 miles before it conks out and needs a recharge.
Battery resting voltage, freshly charged: 12.8 V
Idle voltage at battery: 12-13 V, varies
Rev to 2500 rpm, voltage drops gradually from 12 to 10 V.
Should go up to 13.5 to 14 V.

Stator test is OK, output is about 50 VAC at about 2000-2500 rpm.

I conclude that the rectifier/regulator is probably bad.

I have some questions to ask the people with Harley experience:
1. If I connect the stator output to the regulator, and put a meter on the regulator output, what no-load DC voltage should it put out? (I can't find this test or its spec in the service manual.)
2. Is it common for Harley regulators to become defective with very low miles and always garaged indoors?
3. What replacement brand/type of regulator has been most reliable?
4. Where can you order this brand/type of regulator?

My three bikes are all Hondas, 1976-2006, and I'm more familiar with their problems and where to get Honda parts. I'm just starting to get educated on Harleys.

Thanks!
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It sounds like the regulator is bad. I assume you checked to be sure the stator isn't grounded.

Failures do occur occasionally. HD regulators are generally pretty reliable. I'd just replace it with stock, but Cycle Electric does make some pretty good aftermarket parts.

Not sure why you'd run a no load test, but it should provide output in that configuration. I wouldn't be surprised it the output were a little high without a load.

 

Thanks for the note, nhrider1. Yes, the stator test was OK: 0.2 ohms wire-to-wire, infinity to ground. I went ahead and tested the regulator
output with the meter. I put 50 VAC into it from the stator, and output was zilch.
I ordered a new regulator.
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When you chose this section to post in you seem to have over-looked the several Stickies at the top, which will guide you through checking your bike's charging system! You will need a multi-meter and the instructions should enable you to diagnose exactly what is wrong. Don't spend a penny until you are confident you have nailed the cause! Post any queries.