58 Volt Stator; is that a problem?

[The Voice of Reason]

I have a 1977 GS750 with 23,000 miles.

Sorry for the longish post, but it's having starting problems.

I fully charged the battery (new last summer) and when everything is off it reads 12.9 volts.

Today, when I turned the key, the lights came on, but when I hit the starter button everything went dead. I wiggled the battery a little bit and the lights came on and it started fine (but with just a little smoke from near the negative pole of the battery, close to the gas tank ). So I'm pretty sure I need to clean up all the connections, which will be the first job.

Then I ran the stator tests from BassCliff's pictorial guide. At idle and at 4000 rpm, I'm getting right around 13 volts across the battery terminals. Not good.

I pulled the stator output wires and tested them. The resistance between the legs is about even all 3 ways, around 0.9 to 1.1 ohms. That's good, apparently.

Next, I checked the stator's continuity to ground; no connection at all between any stator leg and the chassis. Also good, if I'm understanding this correctly.

Finally, I checked the voltage output between the stator legs. They were all about equal, at 58 volts AC. And that's my question (finally!): BassCliff's guide says they should be equal and above 60 volts. Is 58 volts really a sign of failure, or do I just have a weak-but-usable unit?

I suspect I know the answer, but hope springs eternal.

Thanks in advance for all the help; I wouldn't know how to even start these projects without the GS Garage and related websites!

The Voice of Reason

[tkent02]

58 could be a sign of a crappy voltmeter. Clean all the connections and run it.

The stator voltages are usually higher, but if everything else works, the battery stays up, don't worry about it until it breaks.

[Nessism]

58 volts is low but not too bad. I'd suspect resistance in the wiring but not positive.

[rustybronco]

At idle and at 4000 rpm, I'm getting right around 13 volts across the battery terminals. Not good.

Finally, I checked the voltage output between the stator legs. They were all about equal, at 58 volts AC. And that's my question (finally!): BassCliff's guide says they should be equal and above 60 volts. Is 58 volts really a sign of failure, or do I just have a weak-but-usable unit?

You need to spin the engine up to 5,000 rpm's and re-check the voltage. 4k rpm's is to low to check the a.c. voltage output.

[1948man]

Can you get too high a voltage? Is it common to see 100 or would that maybe suggest an error somewhere?

[rustybronco]

I think it would be uncommon to see 100 VAC. the only reason that I can think of, is if someone has re-wound the stator with a smaller diameter wire.

[Billy Ricks]

I think it would be uncommon to see 100 VAC. the only reason that I can think of is, if someone has re-wound the stator with a smaller diameter wire.

+1. The aftermarket stators that use larger gauge wire put out slightly less voltage than stock due to fewer windings.

[BassCliff]

Hi,

I don't think 58vAC is too bad either. Clean all the connections and grounds, especially the connections through the fuse box, at the solenoid, the ground strap from the negative battery terminal to the engine case, the stator and r/r connections, and the battery terminals (make sure those connections are tight too). Run the ground wire from the r/r directly to the negative battery terminal. Then re-test. Chances are you'll be OK.


Thank you for your indulgence,

BassCliff

[SqDancerLynn1]

58 v should be OK You should have the early 12 pole stator, reads lower than the 16 pole. I would suggest a Honda reg/rect from Dundage to replace the two piece unit your bike has.. Should fix your problem

[tas850g]

the 12 pole stators read a bit lower than the 16 pole? nice to know this.

[BassCliff]

Hi,

Yes, Lynn should know. She has a '79 GS850G and taught me a lot of what I know about my bike. Thanks Lynn.


Thank you for your indulgence,

BassCliff

[The Voice of Reason]

Everything seems to be ok now

Just a quick status report: I cleaned up the connections and, based on the information here that 58 volts is acceptable output for my bike, it looks like everything is ok. It's charging like a trooper.

I'm still planning to replace the regulator/rectifier, as a preventive measure, but it seems like there is not a lot of pressure to do that right away, so I think I'll go for a ride and order the new part later!

Thanks to everyone for all the helpful information!

Voice

[tkent02]

I'm still planning to replace the regulator/rectifier, as a preventive measure, but it seems like there is not a lot of pressure to do that right away, so I think I'll go for a ride and order the new part later!

As far as I know the R/R never fail if all of the connections in the entire system are truly clean. I have still never had one fail, after twenty or so GSes and hundreds of thousands of miles. I have bought dead bikes with dead R/Rs, they were all corroded at the connections.

[trippivot]

is that at idle? or revved up?

in reality as long as it is over 24~26 AC you are making over 12 DC but I woould not be concerned. that it is a little low from other bikes I have checked if you are getting 58 acv at 6000 rpm your bike is charging.

you might have a higher break even RPM than other bikes.

being that AC Voltage is exactly twice what rectified DC volts are

[1980GS1000E]

How would I know if my stator is "leaking" as suggested in the stator papers? The stator puts out about 75 to 80 volts at 5000 rpm, but the voltage at the battery goes from 14 volts at 2000 to something like 12.7 at 5000. I have good connections and a new r/r.