Well a friend in OK is having fits with a stator/rotor on a 97 EG Voltage reading are only about 5 v per 1000 rpm We need 2 questions answered in simple terms rednecks can understand. BG
#1 When cking the staor output are the volt meter leads (set on ac voltage) Positive and Neg. connected to the 2 wires coming out of the stator. He's thinking you ck eack wire with a pos. probe and the neg to ground. That's not the way I was taught but anyway. Spec says 10 volts per 1000 rpm
#2 Well this is more of situation that got my goat. He replaced the stator a couple of months ago when he got a noise and no charging riding home one evening. When he pulled the rotor one of the magnets had come off and took out the stator. He had ordered a stator but no rotor. He glued the magnet back into the rotor with what witness marks were on the inside of the rotor. If the magnet was installed 180 degrees out from what it was originally could this cause the low voltage readings mention above? Thanks for your time and help WP

 

1. Your friend is wrong.
2. Would cause problems. His exact problem? Hard to say. Cheaping out on stator/rotor/regulator is a Bad Idea. I recommend sticking with OEM HD parts.

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 the battery voltage with the headlight on, bike not running is less than around 11.5-ish, I’d replace the battery. If it’s 10, it’s past it’s prime.

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, depending on your meter. 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. If it doesn’t, you didn’t ground the black lead. 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 Ohms, typically. (Note: Not 200K ohms). Check resistance between the two stator plug pins. Should be fairly low. My Book says 0.2-0.4 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. My book says 19-26 V / 1K RPM.

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.

 

That looks like the definitive test schedule to me, dear Dr.! Great stuff.

 

Thank you Dr. Hess If I may do you have any thoughts about the magnet being reinstalled wrong? If there is a wrong in this case Respects WP

 

The rotor is a single unit, with the magnets integrated into it during manufacture. They are are not 'installed' at any time as separate components. So putting a detached magnet back where it came from is not a reinstall, it is frankly a botch or bodge. Not anything I would do! That rotor is going to rotate at engine speed and the botched magnet will fly off before too long, risking damage to the new stator.

I strongly recommend you replace it asap.

 

Yeah, I'm with Tup on this one. As I said, cheaping out is a Bad Idea. It's been a few years since I've had the rotor off and I don't remember how many magnets are in there. However, strictly from an electrical perspective, if you installed one magnet in backwards, it would, in effect, decrease the magnetic field strength by two magnets worth, as the one magnet would be pushing instead of pulling with the rest and it would cancel out one other magnet's worth of pulling, so to speak. So, if there are 5 magnets in there (I don't recall, as I said) and you put 1 in backwards, then you now have 3 magnets worth of magnetic field working together, or 60% of the total output you would have if all 5 were in there right. Note that I made up the 5 magnet part.

I also bet he didn't use a HD stator or a HD regulator, right? I suggest, again, that after doing my tests outlined above and finding the output of the stator to be insufficient, he suck it up and buy new HD everything (stator, rotor, regulator) and put that on. Vehicles cost money to maintain. A properly maintained vehicle will provide reliable service. One aggie-rigged and cheapped out is a nightmare. What does he want?

You know, there's never enough time/money to do the job right the first time, but there's always enough to do it over.

 

I certainly understand and agree with what your saying. He was just flat stuck and had to get the bike going ASAP. I have mentioned the risk he ran doing this in first place much less what may happen. I'll pass on this insistance in these post to REPLACE IT. Thanks for the help It is appreicated Sir WP

 

I certainly agree He was just flat stuck in a bad situation I'll pass this this on to him I do thank you for your time and help Sir WP

 

Got phone call yesterday from my buddy in OK. With what was said here and the readings he became convinced that a new rotor was in order. Got the rotor off and 2 more magnets had come loose and slid together. LOL I asked him ok are you gonna put new one in or keep running the risk of trashing something. He laughed and said " I have a new one in hand. I'll call when I get back together." He did All is good now and his wife said she was real happy the damn thing is fixed. BG They were headed out to ride some and eat dinner with some friends. Thank Y'all for the help and knowledge WP

Never used an icon before just wanted to see if worked BG

 

I beg to differ Mr B, the magnets on most H-D rotors are indeed stuck on afterwards. 4 speed Sporty owners routinely stick them back on but then add a resin infill between the magnets so that they don't move even if the glue comes unstuck.

Have done it myself a few times, the trick is to get the polarity correct when re-installing.

With 4-speed Sporties the V Twin encapsulated Rotor fixes the problem for ever.