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Discussion Starter #1
Hello, new to the forum and have a question. Im tracing a battery drain issue and was wondering if anyone else with a similar bike could show me pictures of their ground wires. Im pretty sure im missing one that goes from the battery negative terminal to the frame, but have no idea where to attach it. Thank you.
 

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What is currently connected to the negative terminal? Does the bike start/run when the battery is charged?

Do you have a clymer manual or access to a colored wiring diagram? That should make it easy.


There is an issue with these bikes and failing charging systems. On my '79 GS750 I replaced the R+R with a polaris one and it fixed all of my battery issues.
 

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Discussion Starter #3
Ok, so the bike has a brand new stator and a brand new regulator/rectifier. The bike runs excellent. I can ride it for hundreds of miles, but the battery wont have enough juice in it after about 20 miles to start the bike with the push start, but will kick start without an issue and run for a while like that. After extensively looking through picture diagrams of the parts, i think i found the problem, but dont know the best solution....i realized that there was a groind missing from the negative battery terminal. It goes from the negative battery terminal to one of the bolts that holds the battery tray. Then there is another ground wire that goes from that bolt to the frame of thw bike. My problem is that i dont know when to put the ground on thw bike frame. I was thinking of mounting it where the air cleaner assembly is secured to the frame bit was hoping someone on here might have their own 78 that could send me a picture of how theirs is set up.
Oh yea, connected to the negative battery terminal right now is the ground wire for the starter relay, groind wire for the starter, one more that i think goes tonthe instrument cluster, and the last one i just added...
 

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In that case, just get the right gauge wire and run it to a solid ground on the bike.

Also, check the voltage at the battery when the bike is running and rev it up to around 3-4k rpm to ensure it's actually charging.
 

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The negative wire to the battery should go to the frame, and from ther should go to a ground screw on the engine case. Mine has been rearranged a bit. I ran a cable from the battery to one of the bolts that hold down my electrical tray. The second wire goes from that bolt to the engine case.

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Neither of the large cables on starter relay are ground. One goes to batt +, the other goes to the starter +. The starter gets its ground from its mounting points, as does the starter relay. So, whatever the starter relay is mounted to, it needs to be grounded to the frame.
 

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Discussion Starter #6
8ball, you are correct. I had misspoken. So after partial removal of the wiring harness i have found everything so here is my question for anyone following. As you can see in this wiring diagram picture, there is a ground wire that comes off the wiring harness(in the diagram its right above the contact breaker on the lfeft side), does that ground wire get connected to the battery or the bike frame?
Also, i ended up finding the main ground wire which is bolted to the top of the engine case like its supposed to, BUT in the picture diagram it shows that wire being grounded to the battery box with a smaller ground wire going to the negative battery terminal. Is this correct or should i connect the thick ground wire directly to the negative battery terminal?
Screenshot_20210213-092356_Samsung Internet.jpg
20210213_091955.jpg
 

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I believe that one would be in or around the headlight bucket.

Keep in mind Suzuki hasn't designed or built a decent charging system in...well, ever. There are several electrical upgrades that will do wonders for you.. and I would consider the first two must-do mods.

1. ignition coil relay mod. Cut the orange + wire between the run/stop switch and the ignition coils. The relay coil is activated by the + wire coming from the run/stop switch. The other side of the coil goes to ground. Then run a positive wire straight from the battery to a normally open contact on the relay, then the other side of the NO contact goes to the + side of the ignition coil. This mod will eliminate any voltage drop caused by the run/ stop switch and give a solid 12VDC to the ignition coils.

2. Upgrade the reg/rec with a Polaris RZR unit. This will eliminate the old separate regulator, and the shunt type rectifier. The Polaris SH775 reg/rec is a series type and is much much better.

3. DynaS electronic ignition with Dyna 3 ohm ignition coils. This just makes a lot of things better about the bike.

All these mods are touched on in my build thread linked in my signature. Mine is a 550, but it's all the same.
 

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Discussion Starter #8
8ball, sorry if i pick your brain, but you seem to know your way around the bike. So...
1. I see what youre talking about with the ignition coil wire, but what is a 'normally open contact' on the starter relay? Do you mean the post that the yellow/ green wire that goes from the relay to the kill switch, or the post with the power wire? The way i see it looking at the wiring diagram, youre saying to disconnect the coils from the wiring harness and run a seperate wire to eww ach directly from the starter relay instead of going through the killswitch first?
2. I have the ricks motorsports regulator/rectifier, is this no good? The polaris unit looks like it needs modification to work, dont know much about retrofitting anything on these bikes.
3. Im eyeing the dyna s ignition and new coils at the moment but was hoping to sort the charging issue first.
 

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1. Not the starter relay. You ADD a relay. I mounted mine under the tank. Relays have to components: contacts and coils. When you apply power to the coil, it will actuate the contacts. Contacts are either normally open, or normally closed. When you apply power to the coil, it will close normally open contacts, and open normally closed ones.

2.The Rick’s unit is OK but it will suffer the same weaknesses as the OEM one. Did that unit eliminate the voltage regulator? If not, was it supposed to? What are your volt readings across the battery? (Key off, and then again with the engine running at 4000 Rpm)
3. The Dyna S would be after sorting out charging.

The rework of the reg/rec is just some soldering or splicing some wires. You can get the pigtail from a Triumph Bonneville that plugs into the reg/rec, and you just cut the other end and and splice it into the existing wires.

Again, look at my build thread to see all that I’m talking about.
 

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Another thing to consider is eliminating the branch of the rectifier that goes through the headlight on/off switch. It leaves the rectifier as a white/red wire then comes back as a white/green wire into the stator (alternator). You can disconnect the w/r wire coming from the rectifier and plug it into the w/g wire coming out of the alternator. This loop is intended to reduce the charging level when you turn the headlight off. It does this by breaking one leg of the 3 phase output from the alternator to the rectifier. The issue is that they added about six feet of wire and a switch that has the tendency to corrode over time both of which add resistance to the circuit.
 

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8ball, sorry if i pick your brain, but you seem to know your way around the bike. So...
1. I see what youre talking about with the ignition coil wire, but what is a 'normally open contact' on the starter relay? Do you mean the post that the yellow/ green wire that goes from the relay to the kill switch, or the post with the power wire? The way i see it looking at the wiring diagram, youre saying to disconnect the coils from the wiring harness and run a seperate wire to eww ach directly from the starter relay instead of going through the killswitch first?
2. I have the ricks motorsports regulator/rectifier, is this no good? The polaris unit looks like it needs modification to work, dont know much about retrofitting anything on these bikes.
3. Im eyeing the dyna s ignition and new coils at the moment but was hoping to sort the charging issue first.
You're smokin' his brand.
 

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If you decide to re-wire, here's my wiring diagram that I made for using a moto-gadget on my '79 GS750e



 

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One more suggestion: join the gs resources forum. So much info there for the GS line.
 
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