Engine stalls then turning on head- and rear lights

[Dragsdal]

Hi guys.

I recently bought an old GS850G driveshaft MC at a very favourable price. This because of the preciously owner had problems which he didn't have the necessary patience to deal with. Just my luck!

Having tested it out for a few hours prior to buying it, I learned that it's most likely is a problem in either the stator (generator) or the rectifier.

Here's what I experienced: The motor runs fine after having choked it a bit, but then I turned on the lights on the bike (front and rear) the engine starts to run poorly when idling and having trouble with staying running. And the lights dim and clearly needs power. This happends after about 20-30 minutes of driving.

Obviously the lights have some part in the problem
I assume this is because of the extra amps that the lights are using up and therefore depleting the battery faster. The bike is probably not charging the battery or something else is wrong.
Problem is then, what's wrong and here's where you guys comes in.
Can anyone point me in the right direction, whether it's the stator or the rectifier (or a third thing) which is the issue?

I have heard that Suzukies often suffer from bad electrical systems and many of the cases it's the rectifier who's to blame, so if my question has already been answered elsewhere, I would be grateful for a point towards it.
Thanks.

//Dragsdal

[BassCliff]

Greetings and Salutations!!

Hi Mr. Dragsdal,

Check and clean every electrical connection and ground on the entire wiring harness, including the fuse box, ignition switch, solenoid, etc. Run the ground wire from the regulator/rectifier directly to the negative terminal of the battery. Look over these guides:

GS Charging System Health+Quick Test

The Stator Papers

More On The Stator Papers

Cleaning Your Wiring Harness

Fusebox Cleanup

Stator Test

Stator Replacement

Regulator/Rectifier Replacement

Now let me dump even more information on you and share some GS850G lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[tom203]

Hi Mr. Dragsdal,

Check and clean every electrical connection and ground on the entire wiring harness, including the fuse box, ignition switch, solenoid, etc. Run the ground wire from the regulator/rectifier directly to the negative terminal of the battery. Look over these guides:

GS Charging System Health+Quick Test

The Stator Papers

More On The Stator Papers

Cleaning Your Wiring Harness

Fusebox Cleanup

Stator Test

Stator Replacement

Regulator/Rectifier Replacement

Now let me dump even more information on you and share some GS850G lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

All this should keep him busy, if his internet holds up!

[Suzuki_Don]

The first test I would do is start the bike and put a multimeter across the battery terminals on VDC and see wgat the charging voltage is when the bike is running, headlight OFF at this stage. It should be charging between 12.5 and 13.? volts, when the bike is revved up to say 3000 rpm it should jump up to between 14v to 14.5v.

Next test tuen the headlight on and see if you get the same or similar readings. These readings as stated above are what should appear on a correctly running GS.

If you do not obtain these readings then get back to us with your results and we can give more advice.

[Dragsdal]

Thanks for the quick replies (And the welcome )
At the moment it's pouring down outside, and I sadly don't have a garage, so I will make the first test tomorrow, when hopefully it's dry weather again.
To be continued.

//Dragsdal

[Mercaholic]

Exhibits identical problem that I had with two of the stator wires touching eachother after the insulation was worn off.

[posplayr]

The first test I would do is start the bike and put a multimeter across the battery terminals on VDC and see wgat the charging voltage is when the bike is running, headlight OFF at this stage. It should be charging between 12.5 and 13.? volts, when the bike is revved up to say 3000 rpm it should jump up to between 14v to 14.5v.

Next test tuen the headlight on and see if you get the same or similar readings. These readings as stated above are what should appear on a correctly running GS.

If you do not obtain these readings then get back to us with your results and we can give more advice.

The quick test basically delineates those same tests with the options for diagnosing the primary conditions

[1_v8_merc]

Even if your battery is damn near dead, you should still be able to ride it.
The starter will always have problems cranking over with a low
battery.

If your stator is going bad, then you will most likely have charging problems, which can lead to running problems, because there isn't enough juice being generated to keep the spark plugs firing.


You probably need to clean the wiring connections on the bike.
I did that to mine, and I couldn't believe how bright everything was.
Not to mention, the bike ran a lot stronger.

[Dragsdal]

Ok, the weather finally allowed me to make the tests and measurements.
I did the quick test written by you Posplayr (thank you for that) which I noticed was kind of similar to the test Suzuki_Don suggested.

The readings puzzle me a bit, since they seem a bit high - but it may just be my lowcost voltmetre which is offset.
Here's what I measured:
First without turning on lightswitch at all:
1. Battery disconnected: 12.9V
2. Key on: 12.7V
3. 1200 rpm: 14.0V
4. 2500 rpm: 14.2V
5. 5000 rpm: 14.3V
6. Key off: 13.5V

Now with lightswitch on:
1. Key on: 12.5V
2. 1200 rpm: 12.6V
3. 2500 rpm: 12.9V
4. 5000 rpm: 13.1V
5. Key off: 12.7V

Hope this gives some kind of clue.

I also noticed that many of the connections have not been cleaned in a while, so that's probably a good place to begin as you also suggested.
A question about that: how do I clean the molded connectors now that there kinda small and hard to get into?

//Dragsdal

[rustybronco]

Dragsdal, you need to run the rest of the electrical system tests. the reading you are seeing when the lights are on, suggests to me an issue with one of the phases of the stator or an issue with the wiring to those circuits. only further testing will bear that out.

[Dragsdal]

Dragsdal, you need to run the rest of the electrical system tests. the reading you are seeing when the lights are on, suggests to me an issue with one of the phases of the stator or an issue with the wiring to those circuits. only further testing will bear that out.

I will do that and be specially aware of the statortests. Only reason why I only did the initial battery test was because of bad weather (again).
Something tells me, that it is a bad idea to do electrical work on a MC in pouring rain.

Whn I have more data, I will post the results.
Thanks.

//Dragsdal

[rustybronco]

Something tells me, that it is a bad idea to do electrical work on a MC in pouring rain.

Yeh, you'll get wet!

make sure you pay attention to the wiring for the phase which is switched in and out by the headlight switch.

[Dragsdal]

Just came back from a week's vacation, so I wil run the rest of the electrical system tests tomorrow and post the results here.

BTW: I took a run on the bike, and noticed that the battery last a bit longer when driving at a normal average speed, but when i got caught in heavy traffic in the city, which included a lot of stops and idle running, the battery depleted faster and the HUD lights went out. This was when driving with main lights on.
When I then turned off the lights, the HUD became illuminated after a few minutes of driving. I guess this means that the generator just barely is able to maintain the charge when running af higher RPMs, but fail to do so at lower RPMs.
Just thought you guys could use that info.

//Dragsdal

[Dragsdal]

Ok, so I finally got the time to do some more testing and work on the bike.
I cleaned up the fusebox and most (not all) of the connectors and wires in the harness. I actually found a few bad ones, which were wirescrubbed and applied contact cleaner.

Doing the stator test, I came up with these results:
- The resistance between A-B, B-C and A-C was 1.4 ohm each.
- No connection was present between any stator winding and ground.
- At 4000 rpm the AC was measured at 65.2 V between all three connectors.

So, that kinda seem like the stator is working the way it is supposed to....
Any suggestions?

[Fizzyhair]

Duff battery?