electical test ?

[DaveR]

The 79 GS1000 new-to-me project is continuing nicely. The engine purrs beautifully now so on to the electrical. I am electrically handicapped so please be gentle.

The voltage at the battery reads around 12.3V at all rpms. The plastic connector sheath for green/white wire from the stator is melted. All four sheaths at the rectifier connectors are similarly heat deformed.

With the Stator Papers IV in hand, the test results..

Stator - two of the three wires 1.9 - 0 - 0

Rectifier - MM set to diode. The big numbers don't make sense to me but there is some consistency.
-red mm probe to red -
- black probe to yellow ----- no reading
- black probe to white/blue - no reading
- black probe to white/red -- no reading

-black mm probe to red -
-red probe to yellow ------513
- red probe to white/blue - 532
- red probe to white/red -- 515

-black mm probe to black/white -
- red probe to yellow ----- no reading
- red probe to white/blue - no reading
- red probe to white/red -- no reading

-red mm probe to black/white -
- black probe to yellow ----- 516
- black probe to white/blue - 558
- black probe to white/red -- 521

Would I be correct in believing the stator is toast? The rectifier numbers are a mystery. Any advice is welcome.

Thanks, DaveR

[bakalorz]

The 79 GS1000 new-to-me project is continuing nicely. The engine purrs beautifully now so on to the electrical. I am electrically handicapped so please be gentle.

The voltage at the battery reads around 12.3V at all rpms. The plastic connector sheath for green/white wire from the stator is melted. All four sheaths at the rectifier connectors are similarly heat deformed.

With the Stator Papers IV in hand, the test results..

Stator - two of the three wires 1.9 - 0 - 0

Rectifier - MM set to diode. The big numbers don't make sense to me but there is some consistency.
-red mm probe to red -
- black probe to yellow ----- no reading
- black probe to white/blue - no reading
- black probe to white/red -- no reading

-black mm probe to red -
-red probe to yellow ------513
- red probe to white/blue - 532
- red probe to white/red -- 515

-black mm probe to black/white -
- red probe to yellow ----- no reading
- red probe to white/blue - no reading
- red probe to white/red -- no reading

-red mm probe to black/white -
- black probe to yellow ----- 516
- black probe to white/blue - 558
- black probe to white/red -- 521

Would I be correct in believing the stator is toast? The rectifier numbers are a mystery. Any advice is welcome.

Thanks, DaveR

You are not charging.

If you ran the bike for more than a few seconds, immediately charge your battery with a plug in the wall charger till it is fully charged. Depending how deeply discharged it became and how long it sat discharged : it is possibly damaged, perhaps fatally.
(even if you only ran for a few seconds recharge a little bit with a wall charger to prevent a cumulative discharge as you keep testing)

Your R/R readings are good.

If those stator readings are the "AC voltage at 5000 rpm" readings that's bad ... however, if any of the connectors in the path are melted you can't really be sure you are getting an accurate read.
Make sure your meter is set to AC voltage, cut any bad connectors out and connect directly to the wire and check again.
If you still get the same readings the stator is toast


If those stator readings are the stator resistance readings in the stator papers they are indeterminate and the stator could be OK or bad.
(I would tend toward bad, but its hard to get good resistance readings of a stator with a normal multimeter ... Over 10 ohms on any pair would for sure be bad, but all of them below 2 or 3 ohms seems good, although the 0 ohms ones aren't ... but on most multimeters reading ohms accurately below 10 ohms just doesn't really happen ... the fact that they aren't all the same is kind of a bad sign though)

[DaveR]

Your R/R readings are good.

After cleaning all the rectifier connectors and grounds this morning and retesting, the readings are almost the same. Also did some reading on MM use and learned that the diode setting registers in millivolts. A sudden 'duh' moment. Those big numbers are actually fractions of a volt without the decimal. Thankyou for being kind.

Yesterdays stator readings were for resistance. This morning I trimmed off the ends of the stator connectors, stripped back 1/2" of insulation and retested. 1.6 - 0 - 0, nearly the same as the first test.

The other tests from the Stator Papers IV done this morning shows continuity between the stator wires and engine casing are 1.5 - 0 -1.3 ohms, not looking good. The AC voltage at 5000rpm on the three stator wires, approximate as the tach cable is broken, shows only 7.7 - 11.1 - .6 volts. The battery was 12.87V at the beginning of the tests and was 12.65 at the finish. Looks like a new stator for the old beast.

Thanks for your help Martin, much appreciated.

[Normk]

Dave, looks bad for that stator. Others will have equally valid but different perspectives on how to proceed but in case this is useful:

When I worked rebuilding alternators, starters and generators, we used a 50 Watt, 120 volt trouble light bulb as the indicator of whether there was a field or stator ground. Spend time in specialty electrical shops who do this work and you will see that this is industry standard practice.

The bulb is plugged into 120 volt wall socket and one lead from bulb touched to one stator lead with the other wall socket lead to the stator housing. If the light illuminates the stator is grounded. Ohmmeters are not reliable in this test as one can easily prove, or better just ask one of the rebuilders.

I recall that three-phase alternators usually make 70-100 volts when the stator is open circuit so yours sounds very low.

Someone who has worked with a number of this particular stator series may offer insight as to whether there are particular problem areas which can be addressed but failing that: remove the stator and inspect carefully as, unless blackened/cooked areas are present, it is not unheard of to find something which has penetrated the lacquer insulation and is grounding a stator wire.

A customer brought his bike by after the second or third stator replacement. After some poking around, I found that one screw was too long and rubbed through the isulation and grounded the stator. This took some time to happen so wasn't immediately obvious that the cause had not been corrected. On reflection he was able to recall the event which had resulted in the incorrect scew being used.

Bakalorz has deal with much of the subject eliquently in his last post. His caution regarding multimeter testing of VRR is well taken. Resistance values of such components as well as those of any coil such as stator must be suspect unless one uses the meter specified by the manufacturer.

Even with the same meter, results are the only reliable test. I have seem many charge coils and trigger coils which were far out of range in terms of specified resistance but made good patterns on my oscilloscope and, the only test which mattered, the engine ran.

Before you condemn the stator, follow Baklorz recommendation further and ensure that you have stripped the wiring to allow testing from as closely to the winding termination as is possible. It may be that there is a connection issue, again - if the stator is not cooked/burnt.

HIH

Norm

Where are you located, Dave? There might be someone close by who can help of offer test components.

[850 Combat]

Nearly every GS I have looked at since I bought another one about 10 years ago has shown signs of overheating in the connectors from the stator, and also in the main connectors from the R/R. I believe that all that resistance heating in the connectors over works the major components and brings on early failure.

I like to hard wire them now, and have done so on about 6 G's.


Bear in mind that the stator was working when it provided the power to toast all those connectors. Probably the last work it ever did.

[DaveR]

Thanks for the info guys. I removed the stator this morning and washed the crud off with gas - what do you think?

[koolaid_kid]

That is called toast. I have seen lots of them, and that one has gone bye-bye.
If you don't already have a Shindegen R/R, you should probably go ahead and get one of those off fleabay also.

[DaveR]

There isn't much smooth insulation surface left on that stator. Good to have an expert visually verify what the MM findings indicated. You don't recommend using the original rectifier that still tests OK?

[koolaid_kid]

Look at the price of a new stator ($100-$140). Look at the price of a used R/R (~$20). Which would you rather replace next?
I also have an unproven theory that the Suzuki R/R suffers from poor design.
The only thing I have to justify this is my GPz stator, which is the same type and age but is pristine. The only differences are the R/R and the fact that its stator is dry, not "oil cooled".

[Normk]

Dave, that stator is finished. By the time one sees that much heat, the insulation is completely compromised and several to many windings will be shorted.

"850"'s comments regarding stator connections and the need to consider hard wiring/soldering them absolutely matches my views. High resistance in the stator connections is one of the two main electrical problems common to most motorcycle lines. The other common issue being main fuse connections. Both are due to old wiring and poor servicing.

If you don't object to "old and badly serviced" I'll introduce you to my ex-wife.

There are many theories and much mythology regarding VRR types and their advantages/failure points. While I don't share "Koolaid"'s theory, he could be correct and regardless, I applaud him for taking the risk in stating the theory.

These theories tied to personal observations can be catylists to further investigation. The main barriers to identifying the root cause(s) are the lack of sufficient sample size and the fact that few people are able to measure effects.

I do like separate voltage regulator and rectifier installations because they divide the heat and also identify clearly the failure circuit. If one were to see a trend in rectifier failures, for example, it would be simple to acquire a larger capactiy rectifier. Ditto the regulator. The combination VRR units, especially for permanent magnet alternators suffer from heat supplied by both the diode bridge and the regulator circuit. Heat from one circuit could be the reason for failure of the other.

Few people are interested in these factors because they are concerned with repair of one motorcycle.

The condition is made even more marked because the complete assembly is potted. I have had good success with aftermarket stators and VRR's from ElectroSport and some others so would likely roll the dice as "Koolaid" suggests. *Note, not endorsing ElectoSport just stating that the ones I have experienced have been reliable.*

A shop will usually wish to minimize their exposure to risk by replacing both stator and VRR which makes sense both from a business and customer relations perspective. Few customers will appreciate that the shop tried to save them some money if there is a subsequent failure to the "not replaced" item. While I have yet to see a convincing argument for stator caused VRR failure or vice versa, replacing both removes the issue for the shop. On my own bikes, I tend to decide differently unless the warranty from the replacement manufacturer requires differently.

If someone can offer a convincing case, it would be interesting to hear.

Norm

[DaveR]

Thanks for taking the time to write all that Norm. Hope you're nimble with the fingers on the keyboard.

Since there are a lot of things to cover on this bike before next spring and not knowing how much cash it needs injected into it yet, replacing the stator, hard wiring it and the rr connections as 850 Combat and you suggested, as well as cleaning all the connectors, switches and grounds will be the plan for now.

Thanks everyone who replied to this thread.

Cheers, DaveR