electrical problems

[SanderG]

Guy's,

Can someone point me in a direction of what is wrong with my bike.

I own a suzuki gs750 from 1979.

When I went riding the other time, I fueled my bike and wanted to start again my battery was dead ( was only a half year old ).
I couldn't even get my display to turn on. after a minute I was able to get my display back and used my kickstarter to start the engine.
500 meter further my bike just died ( lost ignition I think ) and display was gone again.

When I was home ( had to get my bike on a trailer ) I hooked my battery charger up.
Turned my key to put on my display, and my display was flickering, also my charger wouldn't give a steady amp?rage.
When I pushed my starter button nothing happened.

Already checked my fusebox on the side of the bike and they were all fine.

Really hope you guy's can point me in a direction because with the summer in sight I would love to cruise my GS again

[Guest]

Do the quick test and report back: https://www.thegsresources.com/_foru...ICK-TEST/page9

Sounds like your charging system is not charging, and the above will help pinpoint what isn't working.

[SanderG]

For this test to work, I need to get my bike running I see.
Well I can change the battery and put in a new one to see if that helps, because in this moment he isn't running anymore.

[allojohn]

Check your grounds, battery/engine. You have an intermittent connection.

[Steve]

For this test to work, I need to get my bike running I see.
Well I can change the battery and put in a new one to see if that helps, because in this moment he isn't running anymore.

You can also use jumper cables to connect your bike to your car, but please BE SURE THAT THE CAR IS NOT RUNNING when it is connected to the bike.

When you do get a new battery for the bike, charge it completely before installing it in the bike. It might come with just a partial charge. If you install it and hit it with the high demand of the starter, you will likely limit its ultimate potential. Earlier batteries (many, MANY years ago) would pretty much lock in their capacity to whatever it was when you hit it with the first high load. Newer batteries might not do it as badly, but why take chances? Charge it completely, THEN install it.

.

[SanderG]

Allright I found another battery from another bike.
It say's : Key off : 12,2 volt
Key on with lights 10 sec : 11,6 volt.

I guess this battery is not good enough to proceed?

[SanderG]

So put the battery on trickle loader and got new results:

Key off ( just of the charger ) : 13,3 volt
Key on and (10 sec headlamp) : 12,3 volt

I guess the battery is poor and I should get a new one.
Anyone insight on what to get ( amperage and cca? )

Thanks

[allojohn]

So put the battery on trickle loader and got new results:

Key off ( just of the charger ) : 13,3 volt
Key on and (10 sec headlamp) : 12,3 volt

I guess the battery is poor and I should get a new one.
Anyone insight on what to get ( amperage and cca? )

Thanks

Quicktest
1 pass
2 pass
3 ?
4 ?
5 ?
6 ?

Do the other parts.....

[Gorminrider]

I couldn't even get my display to turn on. after a minute I was able to get my display back and used my kickstarter to start the engine.

well, the obvious is bad connections. especially, look for Black/White stripe wires that attach to the frame or surfaces -the "negative" side of the system...but also check especially Red and orange wires which supply the key switch ...the fuses too.

as to your batteries,

Key off ( just of the charger ) : 13,3 volt

is meaningless. Any battery with all its cells will show this.

Key on and (10 sec headlamp) : 12,3 volt

should start the bike if all else is in good order, which it isn't. It can help a weak battery if you disconnect the headlamp inside the bucket or, pull the fuse for it.

[SanderG]

Allright Update at last:

New battery freshly loaded. ( I think my last battery was a hoax because this one was going bananas on my starter motor, the old one fresh outa shop seemed like it was barely given enough power to turn the motor )

key off : 12,85 V
Key on ( 10 sec with lights on ) : 12,2 V
1500 rpm : 14,2 V ( and it rose till 14,5 after a few seconds )
2500 rpm : 14,1 V
5000 rpm ( more like 4500 ) : 13,9 V
Key off : 13,2 V

doesn't seem to match with what I should get.
I would say the alternator is working.
Is this due to bad connections grounds?
And does anyone know where these are located on the bike, or are they all over the frame?

Thanks in advance !!

[Gorminrider]

"Grounds"? the First and most important is the big black cable from Battery to Engine. You can't miss it. All wires that are on their way to ground are Black/white stripe and they are all connected together-splices are inside the harness...at some point, this is all connected to the frame (and therefore back to the battery via the BigBlack Cable...) with little ring-ended "lugs" ....

as to the 750 I won't guarantee but I'd expect 2 "ring lugs"coming out of the harness. One should be up at the frames front near where the horn is. This is the closest ground for everything in the instruments and headlight. (DoNOT "ground" things directly to the forks) Another might come out of the harness near the battery box..

On the wiring diagram, ground lugs and grounds in general appear as


Remember: Black with White stripe (B/W) and you can't go wrong per the harness. Then there's all the "component" grounds...also attached to frame and often with their own or nearby mounting bolts.

key off : 12,85 V

a recently charged battery

Key on ( 10 sec with lights on ) : 12,2 V

I've seen worse start a bike

1500 rpm : 14,2 V ( and it rose till 14,5 after a few seconds )

yes, it's replacing the power used to start

2500 rpm : 14,1 V

+

5000 rpm ( more like 4500 ) : 13,9 V

doesn't seem to match with what I should get

. looks ok to me. The motorcycle apparently uses more electricity to ignition when it's going faster. Go figure. This means that more of the charging output is being used and therefore while it's still charging the battery, it is nearing its max output. There might be "losses" in wiring, poor connections, a few loops in the stator shorting, or nothing at all. More tests needed if you want to know why it doesn't show higher. An easy useful test would be "Voltage drops" to find if a connector or wire or component is greedy. Also the alternator AC output test . Desccribed in a manual and here too.

I would say the alternator is working

so would I and your regulator too. How well, I'd say "pretty well" ...

Is this due to bad connections grounds?

it's a good idea to keep the battery terminals tight and the electrical connections clean. Look for frayed ,meltedd,blackened connectors.

And does anyone know where these are located on the bike, or are they all over the frame?

as above

Key off : 13,2 V

the battery was charging. Come back tomorrow and it will test lower.

[SanderG]

Grounds sound a solid answer.

When I think about it.

Low RPM means low current flowing from stator ( alternator ) so low Voltage drop.
Higher RPM , higher current flowing from stator so voltage drop increases

So I will be looking for faulty Grounds, bad connections and so on.
I think I will go looking after my bottle of electrical spray.

Quick question: A while ago I saw 1 complete cable harness for my 750 for ? 120.
Is that something you guy's would buy for such an old girl.
Or would you guy's make one yourself or, or?
Because let's face it, electrical cables in the rain, wind, grease, movement for 41 years. that can't be very good.

Kind regards.

[Gorminrider]

How is a used harness with unknown mileage for 120 euros better than your used harness?
Unless yours is badly cut-up or burned, or unless you have dedicated yourself to a Vintage Rebuild, I wouldn't.

[SanderG]

Allright.

So what should I do now? ( because I haven't done anything yet and I don't want to be stranded on the side of the road again anytime soon )

What I thought

1 : Clean/check as many connections and grounds as I can see.
2 : perform the task on the GS CHARGING HEALTH page. So first step 1 : Good R/R connections
3 : perform step 2: Good R/R grounds
4 : Perform the stator paper on the bikecliff site.

Would You guy's suggest something else?

Do you guy's suggest to " change " anything to make it more reliable?

I just want to have a fun/reliable( as possible ) bike to cruise around

Thaanks in Advance.

[SanderG]

on that note,
Where can I find a Working link for the stator papers?
Only find one's with dead ends

thaankss