Charging Question - 1981 GS450S

[Guest]

I have recently installed a volt meter on my GS450

While riding with out the lights on the volt meter shows 14.4 volts

When I turn the lights on the volt meter gradually falls to 12.2 / 12.3 and remains there.

Is this normal - or - does it indicate a faulty/low battery.

[posplayr]

Probably a bad stator; do the quick test and report the numbers. It will be likely you need to follow with phase b ft stir tests especially leg to ground.

[DimitriT]

Sounds like a partially fried stator. I've been riding with a bad stator now for a few months. It will reach 14.6V on the highway but if I stop it will drop to 11.9. I have a replacement stator on hand but I'm waiting for the one I have to go completely before I replace it. Seems like they are only good for 15-20k miles.

[Steve]

I have a replacement stator on hand but I'm waiting for the one I have to go completely before I replace it. Seems like they are only good for 15-20k miles.

Both points of your logic completely elude me.

1. If you know your stator is failing AND you have a new one on hand, why would you not take the hour to replace it? Evidently your regular riding route is TOTALLY predictable and has NO unplanned events, so you can be perfectly confident that NOTHING will go wrong.

2. If you keep a stock R/R in your system, you might be correct in the expected lifespan, but it has been shown that the series-type R/R (Polaris or Compufire) will reduce the heat in the stator, extending its life CONSIDERABLY. Maybe even indefinitely, but nobody has hit the failure point yet, so we don't know for sure.

.

[posplayr]

Both points of your logic completely elude me.

1. If you know your stator is failing AND you have a new one on hand, why would you not take the hour to replace it? Evidently your regular riding route is TOTALLY predictable and has NO unplanned events, so you can be perfectly confident that NOTHING will go wrong.

2. If you keep a stock R/R in your system, you might be correct in the expected lifespan, but it has been shown that the series-type R/R (Polaris or Compufire) will reduce the heat in the stator, extending its life CONSIDERABLY. Maybe even indefinitely, but nobody has hit the failure point yet, so we don't know for sure.

.

If he has a shunt R/R it makes perfect sense.

1.) Using a Shunt R/R the stator is in a constant state of failure

2.) Using a Shunt R/R you have a limited stator life expectancy.

[Steve]

It's also possible that the "headlight loop" has a bad connection or wire.

Without the headlight on that loop is not in the circuit, anyway, so its problem is not noticed. Once the headlight is ON, the lack of the third charging leg will definitely draw down the voltage.

Check the connections of the white/red and white/green wires at the stator-to-R/R connectors, and follow those wires to the connector that might be under the tank or in the headlight bucket. Last resort, check the connections in the headlight switch.

If all those check out OK, change the stator AND the R/R.

.

[posplayr]

If all else fails read the instructions:

GS Charging Health in my signature.

[tkent02]

I have a replacement stator on hand but I'm waiting for the one I have to go completely before I replace it. Seems like they are only good for 15-20k miles.

I have never had a stator "fail" yet, in many hundreds of thousands of miles on about 50 or so GSes. Have bought quite a few dead GSes with burned up stators, but in every case the wiring and connectors were completely fried which caused the stators to burn up too. A little bit of maintenance goes a long ways.

[posplayr]

I have never had a stator "fail" yet, in many hundreds of thousands of miles on about 50 or so GSes. Have bought quite a few dead GSes with burned up stators, but in every case the wiring and connectors were completely fried which caused the stators to burn up too. A little bit of maintenance goes a long ways.

Bigger bikes seem to put more stress on the stator as there is more heat than with smaller bikes.

[tkent02]

Have had everything from 450s to 1100s, no failures yet, except the ones that were failed before I got them.

[posplayr]

Have had everything from 450s to 1100s, no failures yet, except the ones that were failed before I got them.

This is a picture of a brand new Electrosport stator with only 250 miles on it (installed on my 1166 83 ED). After the install i had an oil leak so I had to pull the cover again. I had ridden on the Hiway 33 loop going out of Ojai CA so it was lots of twisties running the bike at 5-6K most of the way.

The R/R was a MOSFET which is SHUNT but puts even more stress on teh stator as it is a very efficient short, unlike the SCR which dissipates a little more power allowing the stator to not get as stressed.

You can clearly see the asymmetrical discoloration of the stator at the upper side (cover is upside down).

So how high of a temperature does it take to discolor Epoxy/PowderCoating?? 350-400 degF. It takes 325-350 degF to cure the paint.

This is direct evidence of excessive heat in the stator windings due to a SHUNT R/R. After the Compufire R/R install the "browning" stopped!!




On my first 81 GS750EX, all I did was clean terminal and add heat sinks to the R/R to completely restore the charging system operation and do it with confirmed low voltage drops between R/R and battery (and retained the original stator and R/R). So I well know that connections are what causes many uncharging problems, but in fact bad connections cause very few if any burned stators.


The point is that there are several factors that affect whether your stator can handle the thermal stress it is under. One of the biggest issues is to not use a SHUNT R/R. Bigger bikes produce much more Hp and therefore heat with relatively the same surface area to dissipate heat.