Almost Stranded. Troubleshooting Advice for PMA/Stock Points Requested

First off... my bike is a 76 XS650C. I have a PMA (appears to be the one Mike's sells, as installed by PO, part# 24-2669) and stock points ignition. The battery is a AGM installed by PO. I don't know how old it, or the PMA and it's components are.

I luckily avoided being stranded for the first time yesterday while about 10 miles from home. When the bike started stumbling, I first thought it was running out of gas. But I quickly realized that when I would turn on the headlight, it would start to die. It did die at one point, but I managed to get it kicked over and running (the electric start just clicked). I just made it home, sans lights. I put the multimeter on the battery, and it was only about 9 volts.

Perhaps this request is premature, as I haven't done anything/testing other than pull the mostly dead battery and place it on the Battery Tender. I'm hoping to get the battery to the point that I can start the bike to measure the charging (or lack thereof) with my multimeter. I do know how to do that much! I just want to be armed with as much pertinent info as possible as I dig into it, since electrical issues are my worst nightmare! I've read the "Expanded Charging System Guide", but it mostly pertains to the stock system. I understand that the "slap test" does not work with the PMA system. I did a bit of searching regarding the PMA, but most of what I found pertains to modified systems and bikes.

Is there a concise guide available for troubleshooting the PMA like the excellent aforementioned guide, preferably with the stock point system? I'm hoping it's just a bad battery... I'm very good at replacing batteries (and bulbs)! LOL Anyhow... any guidance to troubleshooting steps specific to the PMA and stock points setup are appreciated, as are links to threads I might have overlooked.

Thanks!!

Batteries can go bad, enuff to take out charging systems, or make them go whacky.
These simple observations of regular lead-acid batteries could be used to help evaluate AGM batteries.

Using the typical regulated battery charger, rated for max charging current of 6-10 amps, which also has an ammeter display:

Charging a good 12v battery should show 2-4 amps during charging, and drop to 1-2 amps when fully charged.

A battery that is old/sulphated would take 4-8 amps during charging, and continue to draw high amperage when reaching 14v. Usually caused by shorting of the cells by that white lead sulphate deposit that forms at the bottom of the cells.

A vibration damaged battery would take 0-1 amps during charge, and show very little current at 14v. Usually caused by fractured plates, severely reducing capacity.

Combinations of the above, too high or low charging current, and not reaching 14v, or quickly discharging.

Here's a thread that dives into PMA foibles, which would suggest examining the condition of the PMA's coil windings:

http://www.xs650.com/forum/showthread.php?t=30742

Thank you, TwoMany for your response, and for the link. I'll look at that shortly. As to amps while charging, I'm not familiar with how to find that, but will look into that. My skill and knowledge with a multimeter is just a little more than nil. When I hooked up the battery to the Tender yesterday, volts were showing to be around 9 while charging. But I gather that might not mean much. I called my wife a while ago and asked her to check on the Tender. She said the light was now green... so I'm assuming it made it to a full charge. She disconnected it. I'll check it when I get home from work. I have a lot to learn about electrics... but you know what they say about old dogs!

Thanks again!

If that 'fully charged' battery doesn't show at least 12.6v when you get home, I'd declare it dead.

Back in the day, most of our batteries were constructed with solid/flat plates (similar to today's deep cycle batteries for RV's and marine), and could recover from deep discharge. Modern lead/acid batteries use a different construction that promotes high Cold Cranking Amps (CCA), and this type doesn't tolerate or survive deep discharging very well. Once they've been discharged, they rarely recover...

Well darn... replacing the battery would be so simple!! When I got home from work, the battery was at 12.7 (after being unplugged for about 6 hours. I hooked up a12V test light and lit it for 20 minutes. I checked the battery about a half hour after I had turned it off and it was still at 12.7. I think the battery is good. I haven't put it into the bike yet to see if I have a charge or not. That will have to wait until tomorrow after work. But, to thicken the plot, I had put new fuel lines in and rode about 70 miles after that job. The very next ride was yesterday, when I had the problem. I probably was wearing that battery down the whole time in that previous ride, and didn't have a clue. I wonder if I might have disturbed some wiring when I was wrestling with the carbs and airboxes. Hmmm

I'll continue checking it out tomorrow after work. I'll probably install the battery and confirm that it's not charging. Thanks again for all your assistance!!

Battery is good. Was at 12.6 when I got home today. I installed it, and the bike fired right up. The multimeter showed 12.3 while idling. But unfortunately, never rose a bit while revving. So, there is absolutely no charging taking place. All the wires seem to be in place and intact (checked them as they could have been affected when removing/installing the airbox). So the next step is to remove the entire left side cover to inspect the alternator, correct? Should the regulator/rectifier be checked? I'm not entirely sure what to do next. Thanks for any advice rendered!!

Well, you're down to the stator and reg/rec.

Find and unplug the 3-wire stator connector. On the stator part of the connector do the 1-2 2-3 3-1 continuity/resistance test. About 0.5 ohms for each combination is OK. Plus, ensure that none of them have continuity to ground. Lastly, if you can peek about behind the rotor, see if any part of the stator windings look cooked. Could also smell for strong burnt smells around there.

If that's OK, then it's down to the reg/rec. No test scenario for that. Replacement only...

Visually check the three yellow connector. Make sure its not melted, brown or a terminal has come loose and out. Look at the wires as they run down past the sprocket making sure debris or whatever Hasn't damaged the wires.

Check fuse and wire from Rec/reg to battery by checking resistance.

Unplug the 3 yellow wire connector. Check eack wire coming from stator to ground, all 3 should be open. Now check resistance between leads 1-2,1-3, 2-3 each reading should be similar depending on what actual stator you have. Typically under 1 ohm.

Next unhook rec/reg. If you have a diode function on meter great if not resistance is ok. Test red probe from meter to red wire, negative probe to yellow #1, then #2, then yellow #3. Write down each reading. Flip flop meter leads and do same check. You'll notice all opens one direction and low resistance the other. Repeat using the green as base instead of red then yellow #1, #2, and #3.
Notice the pattern? Write it down.

If that checks I'd pop the cover. Remove mag making sure mag wasn't loose on taper. Magnets are loose or cracked. Look of the solder on the stator is dull or shiny? Look for damaged windings and burnt colored wires etc. You'll know.

If that all checks good. Sell it. Jk
LOL with that I'd think you find it!

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I'll dig in tomorrow and get a handle on those tests you mentioned. Thanks, TwoMany!

And thank you, Chizler! You posted as I was posting.

Have you checked your brushes?

I thought a PMA doesn't have brushes. But then, this level of electrical work is new to me!

No you're correct. I had my head up ass.

LOL. I feel mine is up mine with every post and question I write on this subject!

First of all, thanks to all who have replied to my questions!

As I won't get a chance to work on this again until this weekend, I've been reading and condensing your advice, printing it out, and gathering more information I've found along the way. I'm trying to condense all this information to make a simple step-by-step "how to" outline that even I'm capable of following!

In the meantime, I found this Youtube video (about 3:30 minutes long) that shows how to test the stator on a 3 phase PMA. The bike used in the video is not an XS650, but I'm thinking the test procedure portrayed will work for me and tell me if the PMA is good, or shot. It does look simple.


If you have viewed the above video, what are your thoughts or advice? If the PMA tests good, should I be ordering Mike's regulator/rectifier (part 24-2088)?

There is an additional video on checking the regulator/rectifier. Perhaps I should do this prior to ordering a new one?


Pictures and videos are always a help to me. I'm pretty sure my reading comprehension sucks!!

Thanks!!!

Yeah, good choice of videos. All I can add is, in the first 'stator test' video, when checking A/C voltage with the bike running, the stator connector should remain unplugged. It's not obvious in the video, as he has it wedged in there to make it easier to probe from the backside. If the connector were to be plugged-in, the rec/reg would pull those voltages down and invalidate the test...

Thank you, TwoMany! I'm planning on continuing these "extra-curricular studies" and putting my new found knowledge to good use this weekend! I'm hoping to take the mystery out of this system so I "ain't skeered" in the future!

Yes, do both checks before ordering anything. That video of the reg/rec was what I was trying to type. lol
Those are good videos, except IMO and experience it's not needed to do an AC voltage test if the charging system isn't functioning at all. That's more for a weak stator. Like a fellas with lights and fogs lights etc like the Goldwings. Typically the resistance test will be a tell all. But, doing it can't hurt. Unless you lick the leads or something....lol

Will licking the leads wake me up?? The afternoon is starting to drag here! Thanks, Chizler!

"That video of the reg/rec was what I was trying to type." Like I said... my reading comprehension is questionable! I think you typed it just fine! Now, if it had been presented in the format of a child's Golden Book, it would have been super clear to me!

GS Suzukis are notoriously weak on this stuff. On mine I took all three stator wires and soldered them directly to the regulator wires. Even decent plugins can cost you voltage. I picked up a full volt and a half with that simple step, from 12.2 to 13.7. Your PMA should run on the same principles.

Just wanted to add a pointer all ready mentioned, I had the exact same situation many years ago with my first xs650 and back then it were the reg/rec that were in for a replacement. Just a hint...