Good stator or bad stator?! Proper reading?

[Nckgoheen]

I have two stators that belong to 81 xs400's. I'm not positive if they are good or not? I tested them on the 200 ohms setting and both stators had readings of 1.2 on all 3 white wires. Are these stators still good? I know the the manual specs say they should read at .75ohms +\- 10%

Any help would be great!

 

[Yamaguy55]

Probably ok. I'd be suspicious if it were almost zero, or very high. especially if you know the meter is accurate. Be sure to check one lead against the other to see what the meter reads before you use it. If it has a lower range than what you were using, use it. Meters are only so accurate. .75 ohms is almost no resistance. The better test is if you have 13.5-14 VDC at the battery when the engine is running. The stator is a three phase unit, each leg feeds a bridge rectifier in the regulator box. As long as it can make spec voltage, it works. Start with a fully charged battery. Motorcycle charging systems are made to keep the battery charged, not charge it from dead.

 

[Nckgoheen]

Thanks for your quick response Yamaguy55. I just installed a working recitifier and the r 292 voltage regulator that I read works on the xs from other threads. I'll install the stator and we will see how it goes!

 

[Yamaguy55]

check the insulation on the wiring and the contacts in the plug. Between corrosion and bad insulation, more than one old bike has fried their charging system.

 

[XSLeo]

As mentioned touch your meter leads together. This checks the ohms of just the leads. Now check your stator. Now subtract the pretest reading from the test reading to get the actual reading.
Pretest touch the leads gets you say . .5 ohms reading. Your stator checks out at 1.2 ohms. 1.2 -.5 = .7 This is very close to spec.
When I test a stator I look more for the readings on the wires to match each other than the exact ohms. If yours all read 1.2 then it's probably good. I'd use it.
You need to do this pretest leads check on any low ohm testing. Most anything under about 20 ohms do the pretest check. Much above that and it's not so necessary.
Even at that it don't take but a second.
This applies to things like coil primary side, charging rotors.
Leo

 

[Nckgoheen]

The leads together read .3 so the stator wires are .90 so I guess not too far off but each combination the all read the same. I hooked up the voltage regulator r292 I just bought the same way drewcifer wired his according to his thread and I have a working rectifier that's hooked up as well. I started my bike up with the battery reading 12.7 before turning the ignition on. When switched on it read about 12.1, with engine running it read about the same...11.9-12.1.

Not sure where I'm messing up at. I tried the razor trick. Holding a razor up to the stator cover and testing for magnetism but I have none. Anyone have this problem or have an idea as to what may be wrong?
Thanks again!

 

[Lou Ranger]

When you say with the engine running, do you mean idling or revving?
When I was having battery troubles, I did not get a very high reading while idling - what with the headlight being on and the battery feeding the plugs. But when I would rev to say 2,500, the voltage would go up nicely to over 14.

 

[Yamaguy55]

I take it you're not using a Yamaha rectifier/regulator? Be aware that these systems cannot charge a discharged battery. Externally charge battery first. A good battery will hold over 12.5 volts, more like 12.7-12.8. A battery that only gets to 12.0-12.2 is on the way out and will kill the charging system trying to keep up.

With a known good battery, revving the engine mildly should produce 13.5-14 VDC at the battery. If it doesn't, either one leg of the three phase is missing, or one part of the bridge rectifier is dead. Or the actual regulator is kaput.

The field coil has to work. Check it too. The stator is the output of the system, but the inner field coil is what creates the electromagnetic field to make it work, the rotor creates the magnetic force that creates the AC current that then is induced in the stator to supply the bridge rectifiers in the regulator assembly. Well, close to that.
Anyway, check the field coils, and I'd check the price of a factory reg/rectifier or one from Rick's.

 

[Nckgoheen]

Hey Lou ranger, yea at idle it was 12.1 then I revved it to about 3,000 and it dropped to 11.7 volts. What turned out to be the issue on your bike?

Yamaguy55, yea I should probably invest in a dual rec/reg from Ricks. I did the manual spec test for the field coil (looks like a giant metal lifesaver inside the stator right?) which tested at 4 ohms like it should. I'll try and get a dual reg/rec from ricks soon. But I have the original rectifier from yamaha which tests good and I got that regulator that works for xs400's (so they say). You think it's possible the rotor isn't working properly or the field coil could still be bad?

 

[Lou Ranger]

Hey Lou ranger, yea at idle it was 12.1 then I revved it to about 3,000 and it dropped to 11.7 volts ...

I don't know much about electricity, even less when it is coursing through the veins of my bike, but I do know that the voltage is supposed to go up when revved not down. Sounds like Yamaguy55 is your guy on this.

Since you asked though, in my case, it turned out I had a new battery with a defective cell which very quickly got to where it couldn't even turn the bike over. But even with a cell failing, it read higher when the engine was revved.

 

[Yamaguy55]

I don't know much about electricity, even less when it is coursing through the veins of my bike, but I do know that the voltage is supposed to go up when revved not down. Sounds like Yamaguy55 is your guy on this.

Since you asked though, in my case, it turned out I had a new battery with a defective cell which very quickly got to where it couldn't even turn the bike over. But even with a cell failing, it read higher when the engine was revved.

Exactly. The battery could have such a drain that the charging system can't keep up.

Prove the battery is good first. THEN prove the rest. Also, check connections where you can. I'd pull the headlight during the test so it isn't adding more drain.

Your lifesaver is indeed the field coil.

Electricity 101: everything runs on watts. Watts is volts times amps. If the amps goes up, at some point it may actually pull the volts down somewhat. Therefore, if you have a sick battery (I don't care how new it is) is will show a lower voltage with a meter than a fully charged good battery will. A good battery is as stated above. With that battery, you should see 13.5-14 VDC at the terminals with the engine running. That indicates low amp draw and a fully charged battery; remember, this is not a car. Again, it will not charge a sick battery back to health, it has just enough juice to keep a good one topped off. If less output, and you started with a known good battery, look to see what is sucking down the wattage. You cold have a lot of things pulling juice out of the system. You don't need turn signals, lights, horn, etc to make the engine run. You do need ignition and charging. Pull fuses supplying unnecessary stuff. You could have a chafed harness.

In the electronic business, this is a simplified version. Eliminate the side stuff, then come back. It really could be lack of continuity between the stator wires and the regulator on one phase. I'd ohm out from the regulator with it disconnected and the the stator connected. You're going to need to prove each step. If it seems sort of ok, it probably isn't.

 

[XSLeo]

Yamaguy is on the right track. A properly working charging system will charge at around 12.5 or so at idle. It won't charge higher because the rotor isn't spinning fast enough the get the volts up. As the rpms rise the output comes up too. At around 2000-2500 rpms even with the lights on it should reach around 14 -14.5 volts, At higher rpms the reg should limit the output so the voltage never goes higher than 14 .5 volts.
Now apparently you have charging issues because the volts don't come up. You tested the stator and know it's good. The next step is to check the field coil. I'm not exactly sure of the spec for that but on the XS650's I play with it's around 5 ohms. It the ohms are much lower it indicates a shorted field coil. If no ohms it indicates a broken wire. Very seldom do they read high.
On the regulator you have, the R292 will work great. And they can be picked up at most any parts store for less than $20. If your stock rectifier is working then no need to replace. There are more modern replacement that are more efficient. You can find three phase rectifiers on Ebay. I picked up a couple for replacements for around $4 each, these are rated for 35 amps, 1000 volts, plenty for our bikes. To install you hook the three wires from the stator to the three prongs down one side then the red wire to the battery on one prong the black to ground off the other prong. There is a diagram right on the rectifier.
The easy way is to cut the wires of the old rect as close to the rect as you can. Hook these wires to the new rect . This makes it plug in as stock.
Much cheaper than $100 + from some other places and work great.
I'm running an R292 reg and the two Radio Shack bridge rectifiers. Radio Shack don't have the three phase so you need two full bridge rects. $2.98 each.
The Ebay three phase I got look like this pic but are CENTRY brand not XinZen. You can read the wiring diagram right on the side.
They are about 2 3/8 inch by 1 1/4 inch and to the top of the prongs 1 inch.
The body of the rect is aluminum and might be enough heat sink. Bolting it to a piece of aluminum will help keep it cool. Maybe just bolting it to the frame might be enough extra heat sink. I might try it that way. Bolted where the stock one was, Fire the bike up ride it around checking by feel how warm it gets. If it gets to hot to touch it needs more heat sink.
A piece of Aluminum plate 3/16 inch thick 3x4 inches square should do it.
Leo

 

[Yamaguy55]

So, what did you come up with?

 

[Nckgoheen]

Sorry to leave ya guys hangin!

I fully charged my battery and ran it in my friends bike and it's been getting 13.5 volts. So I'm happy about that. Just bought that sucker a month ago. So battery checks out good.

Took my stator and field coil out switched it with the one with better wires and did some heat shrinkin and soldering. I am getting consistent readings on stator of .8 and some change. Poped her back in and hooked it back up with a working rectifier and did the magnetize test by touching a wire to the green lead on the field cool and seeing if the razor blade stuck and it did. So I need a voltage regulator and she should be good to go.

Also I unplugged my headlight and led brake light and checked the voltage before the test I did above and it was still low.
In drewcifer's thread I found out the r292 regulator only works on the later models. Not the 81 xs400 so I need to use the r296 model by BWD or a better voltage regulator if anyone knows of another model?

 

[XSLeo]

On the R292 reg you need to send battery power after the switch to the field coil then from the field coil to the green wire terminal of the reg. Hook the brown wire terminal to power after the switch.
The way the R292 reg works is it senses battery voltage on the brown wire. When it detects low voltage it grounds the green wire to so power cam flow through the field coil.
If you hook these two wires wrong you will instantly fry the reg when you turn the key on. The one I bought from Advanced Auto came with a one year free replacement warranty. I cooked mine once. So back to the store and got the free replacement.
Be extra sure you have the reg wired right.
I have a pic showing the proper wiring of the reg I used. This is on an XS650 so the green wire says to rotor brush, on the XS650 the field coil is mounted in the rotor and uses brushes to carry power to it.
So just think field coil when you see rotor brush.
The diagram also shows how to wire two Radio Shack full wave bridge rectifiers to build a rectifier to replace a stock rectifier. It will work on an XS400 too.
Leo

 

[Nckgoheen]

Hey XSLeo, just wanted to double check. Your post you said r292 and the picture you posted is a diagram for the r295

 

[XSLeo]

I borrowed the pic. The numbers on the diagram are the numbers that were used by the store selling the reg. It says both the R295 as well as a AL154CS.
The one I used was from Advanced Auto. It had a small z on the end but it's still the same reg. I just asked for a reg for a 75 Dodge Dart with the 225 slant six, three speed transmission.
The wiring is the same.
There is a Jeep reg that has four wires instead of the Triangular plug in socket. They will work too but cost about twice as much.
Leo

 

[Nckgoheen]

Thank you for the info XSLeo! Im goin to go get one later this week and get this bike running! I'll let
You guys know how it goes soon. Thanks again to everyone for your help! Lifesavers!

Nick

 

[16VGTIDave]

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