1981 GS 450 charging problem

[rogue1313]

So I'm new to the GS 450 & to the board. I've been searching the forums for an answer, but can't seem to get a simple, concise one.


Bought the bike last week & the previous owner thought there was a charging problem.

Fast forward.....

I'm measuring approx 13.04 VDC at the battery terminals when the engine is running....at all RPM's. (shold be 14.4 or so, correct?)

Per the repair manual, I should measure 75+ VAC on the disconnected output wires from the alternator.....I'm measuring 69 or 70 VAC.

Does this sound like a bad alternator/stator?


Can someone give me a quick breakdown of the correct voltages & resistance readings from the various components (Alternator, Recifier, Batter, etc.)

If the answer is somewhere on the boards, I apologize....but I couldn't find it....there's a lot of talk about the electrical system, but it ends up being more in-depth than I'm looking for.

Thanks.

[Seana23]

Hi babes.

Sorry i cant help you but im sure.someone will be along very soon.....

Its like busses... You wait for ages, then 3 come alobg all together!!!

Welcome to the forum though.
Xxx

[Steel Toed Tank]

That should be good on the three output wires from the stator.
I was keeping my battery charged with about half that, lol.

The R/R is what you want to test next, and this is how

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A22

I found one of my circuits in my R/R blown yesterday and now one leg of the stator is only making 2.5vac!

on this page you will find everything you are looking for and then some.

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html

Good luck!

Tank

[rogue1313]

Thanks, I'll check it out.....

But by all means, if anyone else comes across my post & has something to add, I'd appreciate any further help.

[koolaid_kid]

Thanks, I'll check it out.....

But by all means, if anyone else comes across my post & has something to add, I'd appreciate any further help.

No, Tank has you covered until you report your results back.

[rogue1313]

Right....I"m just saying, hey, if someone has come across a very similar situation (i.e. same measurements), then perhaps they could enlighten me as to what worked for them...no need to reinvent the wheel.

But I'll do some more testing when I get a chance this weekend. I already tried measuring the resistance levels of the Rectifier....but I don't think my DMM is sensitive enough. The manual says that it should measure 5 to 6 ohms....and my DMM didn't register anything...like the range was too low.

I didn't get a chance to measure the voltage output at the Rectifier

[Steel Toed Tank]

I tested my R/R with the diode setting on my VOM/DMM
looks something like ->+

One direction they should measure .500 - .800
other way they should measure OL, or OF, or infinite, depending on the meter.

mine measured .450 .450 .450 one way (good enough)
and OL, OL, 1.178 the other way (very bad)

Make sure you read the directions in the first link I posted above as there is more to the testing than what I just posted now.

edit: Almost everyone has run into a situation like yours, but without your test results we would have no idea what direction to point you in.
It could be a weak battery, dirty or corroded contacts in the harness, a faulty R/R or a number of other things


Tank

[Guest]

It *sounds* like your stator is bad but be sure to do all the tests first.

When my R/R was dead after the rebuild it got to something like 13v just over idle and dropped off as rev's rose, so a new R/R sorted that.

A few months ago my stator died and I was getting something like 40VAC out of each leg of the stator and the R/R was putting out between 12.1 and 12.5v at all RPM and the new stator fixed that.

You need to also verify that all of your grounds are good and also it's best to bypass the stator loop through the headlight and connect all three legs directly to the R/R.

[rogue1313]

Well, first off, avoid buying the IDEAL 61-310 multimeter from Lowe's Home Improvement...P.O.S....it was not working correctly (and it was pretty new)

Anyway, here are my measurements for the R/R:

+ of DMM on the Black & White... - to the other wires:

Red/White 0.508
Blue/White 0.489
Red 0.599
Yellow 0.490 (NOTE..initially yellow read open..maybe just bad contact)

+ of DMM on Red/White, - of DMM to Red 0.525
+ of DMM on Blue/White, - of DMM to Red 0.528

All measurements read OL (open) the opposite direction...so that's good



Tried to measure the resistance per the test the Haynes manual has, but not getting anything...but again, it's talking the 5 to 6 ohms range...probably too low.


They all seem to be within range.

Now the bike is in running condition, but the wiring is definitely sketchy....a bad ground would not be out of the question. However, I'd like to ask again, does 70VAC sound too low for the Alt/Stator output? I'll check again with my new GOOD multimeter.

What do ya think so far?

[Steel Toed Tank]

If all three legs from the stator are the same, then I think that would be good enough.
I had all three measure 30vac when I bought my bike and it started, ran and charged the battery, but then it only takes a couple seconds of cranking the starter to start it, and all my rides are usually an hour or more at 5000rpms.
That of course only lasted about 2500kms before one leg in the stator gave out and took the corresponding diode in the R/R with it.

I would go over the stator papers if I were you, there is a fault finding chart and when I first went over it, I found every fault along the way. Battery not grounded well, R/R not grounded well (very important), voltage drops, etc.

Do that and let us know what you found. Good news about the stator and R/R though!

EDIT: You need to make sure you have a good charged battery for a lot of these tests to work properly.

Tank

[rogue1313]

Might take a quick look tomorrow...but most likely will do a more thorough check this weekend.

Anyway, will definitely post as I go...

Thanks again for the advice so far

[robertbarr]

However, I'd like to ask again, does 70VAC sound too low for the Alt/Stator output? I'll check again with my new GOOD multimeter.

Stator looks OK. 70V should be fine.

IMO, the only R/R measurement that matters is: Does the darn thing work?

If properly wired -- SOLDERED connections from stator to R/R, heavy enough SOLDERED wires to the battery (through a SOLDERED fuseholder) -- you should get better looking voltage output.

This much soldering is perhaps a ten minute job; getting clean bare copper is most of the battle. You can add a few minutes if you're going all-out on appearance, but it's fast & easy. Even to test the R/R, solder it in there. If you wind up replacing the R/R, you still have enough wire length to cut off & replace the solder connections.

Still not adequate? Replace the R/R with a unit that's recommended from this site.

This stuff is simple. Not always easy, but simple. There is nothing unique about a particular motorcycle (three--phase, anyway = most UJM's) that requires extensive study or troubleshooting -- it's always the same story.

Good stator + good wiring = an either/or test for the R/R. If you're not getting adequate output, it simply has to be the R/R.

[rogue1313]

Yeah the wiring LOOKS all of it's 30+ years...I"m sure that's not helping the situation.

It runs pretty smooth, but it's a project...so things will have to be gone through for sure.....But it would be nice if it could be sorted out easily


Thanks for all the insight....keep it comin....I'll update as I go along and see what I find out.

[rogue1313]

Did some preliminary cleaning of ground contacts & took some measurements with my new, working multimeter.

Voltage at the battery is a little higher...up to 13.4 when you rev it...but could just be the better multimeter reading it more accurately.

Sill measuring around 70 VAC off the Alternator/Stator leads....one or two of them will go as high as 74VAC at 5000rpm...again, could just be the multimter.

Left the battery hooked up overnight & the volatage remained about the same....no significant drop....so at least it doesn't look like there's a short that's draining the battery.

I did notice that the green/white wire off the Alternator/Stator seemed to be warm to the touch while the bike was running....at least felt warm compared to the other 2 wires.....I'm wondering if that could indicated a problem with the particular line. Like it's working harder or there's more resitance causing it to heat up. It's warm, not hot.

I also noticed that when I unplugged the green/white wire, the engine idled slightly faster. When I plugged it back in, the idle slowed down.


I need to get in there and just clean all the wiring off.

I did have another question......The black/white ground wire of the R/R & the apparent ground wire to the I think it's the Ignitor right next to it.....both ground wires have round eyelets at the end are ultimately bolted to the metal plate that holds the R/R, Ignitor, starter relay, etc.

I'm curious.....that plate is bolted to the frame, but here is a rubber grommet that appears to isolate it....and the bottom of the plate has a tab that just fits into a hole of tab on the frame.

Should those grounds be bolted/make contact directly with the frame? That plate doesn't seem to make siginicant contact with the frame to make a good ground.

You guys get what I'm describing?

[koolaid_kid]

The best ground solution is to run a wire from that common grounding point (bolt) straight to the negative terminal of the battery. So you keep what you have and make another ground wire, round eyelet at the bolt end and whatever works with your battery terminal at the other end.
And yes, we understand.