Lights go from dim intensity to bright, back to dim...back to bright.
Is this a stator going bad ? Voltage regulator ?
I hate th' "if it ain't broke, don't fix it" plan, especially if I'm out 400 miles, cruisin' at night.
What's YOUR thoughts ? Got a FIX ?

 

I would start by checking connections to make sure there clean and tight.
Next step would be to follow the flow chart in my service manual.


Bob
97 Heritage

 

Dr.Hess' How To Diagnose Your Charging System

Buy about a $10-20 digital multi meter. Fully charge the battery (overnight on a 1 amp charger).


Scale on DC Volts, around 20V max voltage scale. Nominal readings are given in brackets. Check voltage across battery terminals (12.8). Turn bike on. Check voltage (less than previous, ~12.0+, depending on headlight, accessories). Start bike and let idle. Check voltage (could be 12.0 to 15). Rev to about 2500. Check voltage (should be more than observed with bike on but motor not running, and more than with bike off. Ideally between 13 and 15.) Turn high beam on. Should be about the same, give or take a little. If the voltage is over 15 or 15.5-ish with a headlight on, I'd consider replacing the regulator and/or checking all grounds (battery to frame, regulator to frame in particular).

If you pass the above tests, your system is most likely fine, including the regulator and stator. If you don't pass, then:

Bike off. Meter set on Ohms, medium-ish scale, like 20K or 200K Ohms max scale. Pull stator plug. Ground the meter black lead to a good chassis ground, like a bolt or even the battery negative. With the red lead, touch a different part of the bike, like the engine case at an unpainted part or another bolt. Meter should read low ohms, like 0. With the red lead, touch each contact on the motor side (stator) of the plug (the part stuck in the case). Depending on if your case has a male or female plug, if you can't see the metal part/pin of the plug, you can put a paper clip in the hole and touch the paperclip with your meter red. Meter reading should be infinity on all pins. If it isn't, your stator is shorted to the case, replace.

The following is for single phase systems. I don't have a multi-phase and haven't had to diagnose anyone elses, so I haven't dug into those systems.

Set meter to lowest ohm scale, like 200, typicaly. Check resistance between the two stator plug pins. Should be fairly low, like a few ohms. The spec is in your shop manual. If it is infinity, stator is blown open. If it is 0, stator is shorted to itself.

Set meter to AC Volts, 100V scale. Attach each meter lead to a stator pin. You may need to rig up some type of temporary plug. It is important that nothing can short to ground or to each other accidentally, or you will blow the stator if it wasn't blown before. An old plug off of your last regulator is a good way to do it, but, get creative and be careful. I can do it holidng the leads on the pins once the bike is running, but I don't like to. Start bike. Voltage should vary with engine speed. Specs are in your shop manual, but 35V at a couple thousand RPM is probably about right.

If you passed that stator test and failed the first test, your regulator is shot. If you failed any part of the stator test, replace both regulator and stator.

 

Thanks Doc.... that ought to get it. Sounds like this isn't your first RODEO.

Twodogs

 

Yeah, not mah first rodeo. Learned me diagnosin' HD electrical systems on SHOVELHEADS, when you had to replace the whole thing only every year if you were lucky.