[WFO-KZ]

The other important thing that the service manual states is to NOT engage in charging system or electrical troubleshooting without first making sure you have a good battery. This step is often overlooked.

All electrical testing done with sub-standard battery can be totally useless and send you in the wrong direction. If the OP has not confirmed he has a healthy battery then I would advise charging it fully and then taking it to a shop and have it load tested.

 

[bweighmaster]

I think you should seek professional help ....

 

[WFO-KZ]

Who me? or the OP?

I once saw a sign that said "you never see a motorcycle parked outside a psychiatrist's office".
So I would argue none of us need that kind of help. Motorcycles keep us sane. 🤪

 

[zx_kz]

I think you should seek professional help ....

I wish I know a reliable professional around me....

 

[Kawasakian]

From what I have read in this post, you really need to have the correct battery for you bike. The 2 video links will tell you how to measure the stator. Purchase the Factory Service Manual, it will pay for itself in this one repair.

 

[bweighmaster]

I wish I know a reliable professional around me....

Sometimes you can find help by asking around the local watering hole , or the local riding area ... Somebody will get you in touch with the right contact ....

 

[WFO-KZ]

Kawasakian makes a good point. Not only do you need a healthy battery, you need the correct battery. I note that your bike came equipped with a battery sensor. The question becomes, what happens when the sensor is disconnected to install an non-oem battery?

There are threads on this site to explain what you have to do to bypass the battery sensor.

My understanding is the sensor is there to warn you when the battery electrolyte level gets too low. But what other action might it take? Well in my view it might send a signal to the junction box to stop charging. This would prevent boiling the battery dry. This would explain why you are not getting charging voltage at the battery. Might be worth looking into that.

 

[1981GPZ550]

I would agree with the correct and healthy battery advice with one exception, the no load phase to phase test. This test is ( assuming the motorcycle can be started) independent of battery condition. Also be aware, and I have experienced this personally, a good no load voltage test is not a conclusive indicator of stator health. I once had a case where the stator was putting out great voltage but was totally fried. Again the difference between voltage and amperage. With all the good advice the op has received I would recommend phase to ground tests and or simply removing the alternator for a look. No mistaking a fried stator.

 

[Kawasakian]

I agree. The heat produced could make a Stator fail when it gets hot. Removal of the Stator with a good visual inspection, and a good impedance reading will tell you much.

 

[haybaler]

"I wish I knew a reliable professional around me...."

I think we are the reliable professionals, but remote instead of near you. And, fixing motorcycles ain't easy, especially fixing some of the brilliant designs from the 80's; wow, those were the days of innovation! But even back then technicians howled over difficulty troubleshooting, and savvy technicians kept a few spare "known good parts" at the bottom of the toolbox, to plug in for troubleshooting. So at this point, I would buy a parts bike and swap out the entire electrical system, that'll fix her!

OR

Can someone post or send the wiring diagrams of the ignition system and the charging system, or the entire wiring diagram? Maybe it's something to do with the charging, so I agree with all the suggestions above, but maybe it has more to do with the ignition system; it's a mystery why plugging in the rect/reg brings the symptom. What circuits does that affect other than bringing in the stator, and sending voltage to the battery?

 

[1981GPZ550]

Because these are battery ignition machines. Many Japanese single cylinder off, or on off road motorcycles are magneto ignition and do not need a battery to run but that is not the case with most street bikes. Without the reg/rect in place the system is basically open and operating as constant loss. Install the reg and the system is now integrated with the stator. Any fault in the wiring from the alternator, short between phases of short to ground will pull the electrical system down robbing power from the ignition.

 

[haybaler]

Because these are battery ignition machines. Many Japanese single cylinder off, or on off road motorcycles are magneto ignition and do not need a battery to run but that is not the case with most street bikes. Without the reg/rect in place the system is basically open and operating as constant loss. Install the reg and the system is now integrated with the stator. Any fault in the wiring from the alternator, short between phases of short to ground will pull the electrical system down robbing power from the ignition.

Okay, so that's a good theory, very scientific, you may be right, but can we prove it? Well, one way is to replace the stator and fix all the connectors, and see what happens, right? Another way would be to test the ignition system to see if it's actually being "robbed of power", perhaps a voltmeter at the ignition coil, or a voltmeter at the Ignition Control unit, or even a strobe timing light on one of the high tension leads. Then by your theory, when the abnormal running occurs, the voltage reading (or consistency of spark) should show at one of those points, right? Does OP want to try that diagnostic?

 

[Kawasakian]

Reading this thread again points to a bad Stator, possible a R?R. Those components changed, with wires running straight to the R/R, and the +/- running to the battery should get your bike going. This would be pass any wiring harness problems, and the lead from the R/R to the battery terminals will be extremely short.

 

[jpd]

Kawasakian The test in the Partzilla test is the same as mine. Except I recommended doing it at a stable 2000 RPM and I called the wires A, B, C, not 1, 2, 3. The 3 combinations make up the 3 phase AC that is going to the rectifier to be rectify into and regulated DC voltage.The bump in RPM will put the stator at just a little higher output and the other forum I got it from has stated it will detect even a 1 or 2 winding short. The construction of the stator will run each wire in and wrap it around its set of poles forming coils. Then the other end of all 3 wires are connected together. So when you test from one wire end to another wire end you are checking 2 sets of coils. You have to do this with all 3 wire combinations. I didn't mention it but yes you need to start the testing with a fully charged and good battery as the bike will be running off just the battery during the tests.

The shop manuals I have recommend testing the stator with resistance checks. Unless you have a very good quality meter you will never read a 1 or 2 winding short. It will detect a short to ground, as shown in the video.

If the regulator function is faulty the output voltage at the battery will be too high and can cause damage also.

 

[Kawasakian]

The 3 leads rom the stator can run to any of the inputs of the R/R. The DC output will tell you what you need to know. It should be around 13.8 Volts DC. Any higher, or lower, either your Stator is bad, or your R/R is blown. Problem here is that he has put new components onto a possible bad Stator which may have burned out his regulator/rectifier. He'd have to have a really good meter, like a "Fluke" or something to find one or two bad windings, but the windings are run on a single insulated wire, so if one wire is busted, that Stator leg won't work. Sometimes this only shows when the Stator gets hot, and then that leg of the Stator fails. If you have one winding testing to ground, that Stator is shot. If the system can't rectify and regulate to 13.8 volts, you charging system is bad. The diagnosis comes afterwards. Since the diagnosis was not done properly, essentially he is an the beginning. If it where me, I'd get a new stator and R/R and go from there (Oh, and the proper battery too) It's unfortunate, but money may have been wasted, though he has not purchased a new stator, or battery, so it can't be that much. This is starting to get circular.

 

[WFO-KZ]

One correction to what Kawasakian says about DC output voltage from the R/R.

Factory service manuals for most big bore, 4 cylinder engines including GPz and KZ1100's says "14.2 to 14.8 volts" or "less than 15 volts" is acceptable. I know this sounds a bit high but I checked in several manuals and over a range of many model years so it's not a typo.

 

[jpd]

At $454.00 for a new stator from Partzilla I sure would like to know for sure it is bad before I bought one. Not his bike but my Vulcan 750 also required removing the engine to access the stator. So about 4 hours labor just to get to it for visual exam. The original stator lasted about 60,000 miles the first cheap replacement about 5,000. With the amount of work to replace it I wish I had put in an original at 4 times the cost.

I am also thinking it is a bad stator, and /or possibly a bad RR or two. I am just recommending verifying a bad part before just replacing it.

 

[WFO-KZ]

Agreed on the need to be sure it is the stator or at least remove all other likely problems before replacing this expensive part.

This is getting circular as stated by Kawasakian, but if it were me I would do the following:

1) I would install correct size battery and make sure it is fully charged.

2) I would investigate whether the OEM battery sensor was properly bypassed.

3) If no joy, I would conduct all stator tests that have been outlined so far and/or covered by the factory service manual.

4) If all stator test are good, and still no joy, then I would follow the factory procedure for testing the R/R. This is a bench test that involves two power sources, one at 12 VDC and one at 24 VDC. If R/R passes the test, then I would run new wires directly from stator to R/R.

5) if still no joy, then in my view there are only two possible sources left for lack of charging voltage.

a. The stator is defective, or

b. The rotor has lost enough magnetism that it cannot create a strong enough magnetic field. The manual warns that dropping the rotor or impacting it can cause it to fail, so don't discount this possibility.

 

[zx_kz]

I did checked alternator and R/R today.

I did stator static test as the video from Kawasakian. The result is "Ol", no issues.
I also followed the service manual page 5-6 and 5-7 "Alternator Inspection". The result was 0.5 ohm which is in the range (0.36 - 0.54, according to the service manual).
I did not open the alternator cover for stator visual inspection today.

Rectifier inspection (Service manual page 5-7). No issues.
Regulator inspection test 1 (Service manual page 5-7 and 5-6). Light didn't lit. No issues.
I can't conduct the Test 2 because I don't have 24V power supply.

Regarding the battery. What I have is YTX20L-BS which is applicable for GPz1100 B1 and B2. I am using it since 2015. Before I bought the first one in 2015, I asked to Yuasa if there are any issues to use it to GPz1100A. Below is a response from Yuasa.

Originally KZ1100B (82 only) and 83-84 GPZ1100 took special battery for use with acid level sensor on dash board.
The battery was SYB16L-B. Which actually has since been discontinued. We say to use YB16L-B for these, and disable the sensor.

In these cases, and the other Kawasaki 1100 models that you mention, it is possible to substitute the YTX20L-BS.
Main difference (other than being AGM) is the width of the battery. YB16L-B was 100mm, YTX20L-BS is only 87mm. So you may have to add a spacer of some sort to keep battery from
moving.

As far as charging system requirements ...
And time you are changing a conventional battery, and using an AGM instead, you should check capability of your motocycle's charging system.
At 2,500 - 3,000 rpm, you should see at least 13.8 volts to be able to maintain the battery decently.
http://yuasabatteries.com/faqs.php?action=1&id=30
If voltage is lower, or bike is not consistently run at those RPM's (highway use), you may need to supplement the charge on the battery to keep it 100% charged.
This means periodically putting the battery on a maintenance charge. At least once a month.

Putting an AGM in an older application will not typically shorten the life. In fact, you will probably still get longer life out of an AGM, as they are designed to last longer overall,
As compared to a conventional battery that has an average 2-3 year life.

After I revisited it, I have feeling that using YTX20L-BS is not the cause... I need to recharge it before I do testing though...

My GPz's battery sensor was disabled by the professional 20 years ago (It could be more 20years. I don't remember...

Next move will be stator visual inspection, to find out how I will have Regulator inspection test 2 and wire harness check.

 

[Kawasakian]

I think it's your Stator. I believe it's happening when the Stator gets hot. Since the R/R checked out, I would wire it the way I recomend and see if you get the right output voltagee to the battery. Just out of curiosity, what is the output at the battery now, when bike is idling, and a little revving? Coils can get really wonky when they get old, and hot, they will come on and off. Do you have a spare set of coils around ? Check the connections of the coils in any event. If the leads unscrew from the coils, unscrew then, and maybe cut off 1/4" inch and screw them back in . Take a picture so you know where everything goes.