Charging Diagnosis Required

[Suzuki_Don]

I know I should have done a search. I did. Just need something verified if that's possible. I've read the STATOR PAPERS and these are the test results on my '77 GS550B model. It still has original stator, rectifier and separate regulator.

Voltage across battery at idle is 15VDC, 17VDC at 2000 rpm.
20VAC at idle between the 3 stator wires on all legs.
60+VAC between the three legs (3 tests) at higher revs, about 4 or 5 thousand.
7VAC between each stator leg and ground at idle.
Doing the stator test in section "B" where the reading between the 3 stator wires is supposed to be between 0.5 to 2.0 ohms. It appears to have one faulty wire. The readings were 5.8 ohms, 5.6 ohms and 0.9 ohms.
Can I get away without buying a new stator because the AC voltage at revs is up to 60VAC which seems enough to supply the rectifier or are the sub standard ohm readings on the stator mean it has to be replaced. If so where is the best and cheapest place to buy a stator.

I am also going to replace the rectifier and regulator with a common unit from a Honda when one turns up on Ebay.

Sorry for being so long winded.

Please help.

Don

[chiphead]

IMHO you should not have any voltage between the stator and ground. Replace it now. Again, IMHO.

[duaneage]

Probably a burnt stator that is shorting between two of the legs and possibly the case. The third leg will soon go and that will be that.

[tomm]

I don't have anywhere near the experience that other GSR folks have with these types of problems, but I'm not convinced yet that you have a bad stator. However, they are free to tell me off if they think I'm totally out in left field here, and I'm sure they will (nicely, off course) .

The fact that the resistance is a little off could just be the connection between your probe and the stator lead. If it really is almost 6 ohms, that is high, but a short between stator legs or an open wouldn't result in that reading I would think. Everything else in your numbers says that the stator is OK. I would expect some AC voltage between each stator output and ground, although I can't say that 7 volts at idle is correct. Would sound about right though if you are seeing 20 volts between legs.

60 volts between legs at high rpm I would think is good.

What has me concerned is 17V across the battery at 5K. That sounds high. I would replace the R&R first and clean all your connections. Probably do that fairly quickly, as a problem there could easily take out the stator and battery. Then test again. If things don't look right at that point, then change the stator. Either way, the stock R&R is a bad design, so best to get it out of the equation regardless.

[Suzuki_Don]

I think I will replace the separate rectifier and regulator with the Honda R/R unit to see if I can get the correct voltage across the battery, I have one coming from Duane. Also can anyone tell me if I disconnect the wiring to the AC pole in my lighting switch will I lose the DC voltage required to power the lights, etc. If so what is the solution.

Regards
Don

[tomm]

Actually, disconnecting the lead from one leg of the stator through the lighting switch and back to the rectifier is part of the aforementioned bad design that you want to get away from. It will not affect your lighting. Just connect all three of the output leads of the stator to the three rectifier leads of your replacement R&R, and tie off the leads that went from the stator to the lighting switch and back to the rectifier. Very important to make sure that the new R&R is well grounded. Preferred connection is directly to the battery negative. And as you've probably already read elsewhere, replace the banana jacks with blade connectors. This is a high current area, and a poor connection anywhere here is going to be trouble.
Good luck.

[Suzuki_Don]

Thanks Tomm. I thought that was the case, and I did not want to replace the lighting LH switch as it is working perfectly.

Regards
Don

[duaneage]

I think Don's RR took out the stator, the new Honda RR on the way to him won't be affected by the bad stator, but it won't fix the stator either. I've measured a lot of stators from Suzuki bikes the good ones always read .8 - 1.0 ohms across any two legs, the bad ones were 4, 8, even 20 ohms across one or more.

More to the point about replacing the stator, electrosport has a handy reference chart showing what model of replacement stator to use with each model and year of GS bike. It also gives an idea of which models are compatible. The early GS bikes used a different, smaller stator with 10 poles the models made after 81 used a 12 pole model and were larger. I would suggest buying a stator new unless your prepared to measure the resistance of the legs in a boneyard before you remove it. Getting them out is a dirty task, I would want to replace it with a new unit once rather than do it twice. Since stators can be damaged by faulty regulators, buying them used is a dicey affair. They also can be damaged by an overheated bike since they sit in oil. Rumor has it low oil levels also can damage a stator.

One more thing, when measuring the legs, touch the ohmmeter leads together and "zero" the meter so that it reads 0.00 ohms that way. If not, the reading will not be accurate. To measure a stator properly the meter must first be zeroed. Older analog meters had a wheel that could adjust the needle to zero, newer digital models have button that zeros the meter when pressed

[SPARKSS]

More to the point about replacing the stator, electrosport has a handy reference chart showing what model of replacement stator to use with each model and year of GS bike. It also gives an idea of which models are compatible. The early GS bikes used a different, smaller stator with 10 poles the models made after 81 used a 12 pole model and were larger.

Thanks for putting up the link to electrosport. I was surprised to see your info regarding the number of poles used on some GS models, in particular the 10 pole reference as a 3 phase winding requires a number divisible by 3. My 79 GS1000 for example has an 18 pole stator.......though the last time I wound it I only used 9.....winding 3 only in each phase (every other pole is now empty).

[duaneage]

Somebody up here talked about them being 10 pole versus 12 for the later. I don't know where it came from. The stators for many GS bikes are actually interchangeable as are the regulators.

[tomm]

I'll be interested see how this one finally turns out. Please keep us informed of your progress Don and what you find after replacing the R&R.

I agree that 6 ohms is high between any two legs, although I don't have the personal experience of measuring many stators myself for comparison. But wouldn't expect all the voltage measurements to be what was posted if the stator was really bad. Any thoughts on that?

Point is well taken though about zero'ing out the meter first, making sure the meter connection is good, and making sure that nothing else is affecting the reading.

[duaneage]

It might put out 60 volts into a meter but under load might be a different story.

[tomm]

Good point!!