'81 GS 750 Wiring/Ignition Issues

[Rex]

I bought a disassembled '81 750 as my first bike and a first major project a few months ago. I'm no stranger to tools or to figuring things out, and I have both a Hayne's manual and the Suzuki shop manual. I have everything reassembled, but there are some wiring issues that I just can't figure out.

When I got it, all the wiring was unplugged and some of it was even cut and very shoddily put back together. Also, the CDI box was destroyed by the previous owner. I've spent quite a while figuring out which wires go where, and I believe I have them all connected correctly. I even got a new CDI box the other day and hooked it up. However, I am not getting a spark at all, nor will the headlight or taillight work when I use the light switch. The tallight works when I hit the front brake, but not the rear. The engine cranks over and all the other electronics work, the plugs just won't spark and those two lights don't work. I am at my wit's end! I've spent quite a while getting this bike to this point and I want to see it finally run! Any suggestions?

 

[Steve]

First of all,

Any suggestions?

Sounds like you need to sit down and scrutinize the repairs made to the harness. Follow them to make sure they are correct. It's going to take some time and effort, but you need to know FOR SURE that it is correct.

Where are you? One of us might be near enough to you to stop by and give a hand. Click on the User CP tab in the upper left corner, go to the Edit Your Details option and add your location. It will then show in the upper right corner of all your posts. It's also nice to add your bike to a signature so that you don't have to remember to mention it every time you ask a question.

One last item:

.

 

[BassCliff]

Greetings and Salutations!!

Greetings and Salutations!!

Hi Mr. Rex,

Yep, I think you're going to have to go over the wiring diagram and carefully trace each circuit. There's really no easy way. You might consider buying a used harness from ebay, if you can find one. I'd be surprised if any are still being sold new (or NOS).

Anyway, 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", the Carb Rebuild Series, and the Stator Papers. 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

 

[Guest]

Wire the ignitor straight into the battery with jumpers to see if you can get it to fire.
Is the kill switch good? Are you getting power to the coils and ignitor?

 

[BassCliff]

Hey Rex,

I collected this little Gem from Mr. Steve and put it on my website. It pertains mostly to a GS850 but it may help you figure out what's going where.

Simplify The Wiring Diagram



Thank you for your indulgence,

BassCliff

 

[Steve]

I collected this little Gem from Mr. Steve ...

Hey, I know that guy.

.

 

[Guest]

Hey, I know that guy.

.

Better than you may think

 

[Rex]

Thank you, BassCliff and Steve. Your suggestions have been incredibly helpful. I ended up buying a new wiring harness off of ebay, and I've found a few more things that the previous owner did to the electronics as a result. Everything is hooked up properly in the rear, and I am going to visit the salvage yard tomorrow to replace a few more parts that he mangled. Hopefully everything will work properly after that!

I especially appreciate the link to the ignition troubleshooting site. It is very detailed and informative, exactly what I needed! Thanks again!

 

[thirdgen427]

81 GS1100E Wiring nightmare

81 GS1100E Wiring nightmare

Ok so i got a real stumper, ill start off with this its a 1981 GS1100E with 14,000 miles on it and were talking original tires mint and always garage kept. So last year i noticed that the bike was not charging the battery, everything else worked great except for that, aslo noticed that the rectifier wires were getting so hot that they were melting the insulation and the plastic covers on the connections. So a simple rectifier replacement took care of that, but then one day riding home all the lights (dash,headlamp,brake,and turn) dimmed out as if they were only getting 6V. After i got barley got home the whole bike just shut off as if you had disconected the battery cable, no power anywhere but all the fuses were still good. So i replaced the battery cables wich somewhat fixed it but for some reason the whole check pannel is lit up and i have no turn signals, or brake lights. the high and low work fine as do all the running lights except for the signals. also my nutral light stays on and sometimes the oil light will also. And to throw off whatever you were thinking it still has this prob with the regulator unpluged (while the bike is not running of course) also still has brake light prob with turn signals unpluged. i pulled back the sheething in the main harness and have spent days looking for burnt wires or bad connections but found nothing the harness is 100% un hacked stock. i even tryed replacing the battery and this led to the bike not starting with the start button, but if i jump power to the trigger wire on the solinoide it fires right up, ignition is not effected. any help woulkd be greatly appreciated. Thanks Brad

 

[posplayr]

Ok so i got a real stumper, ill start off with this its a 1981 GS1100E with 14,000 miles on it and were talking original tires mint and always garage kept. So last year i noticed that the bike was not charging the battery, everything else worked great except for that, aslo noticed that the rectifier wires were getting so hot that they were melting the insulation and the plastic covers on the connections. So a simple rectifier replacement took care of that, but then one day riding home all the lights (dash,headlamp,brake,and turn) dimmed out as if they were only getting 6V. After i got barley got home the whole bike just shut off as if you had disconected the battery cable, no power anywhere but all the fuses were still good. So i replaced the battery cables wich somewhat fixed it but for some reason the whole check pannel is lit up and i have no turn signals, or brake lights. the high and low work fine as do all the running lights except for the signals. also my nutral light stays on and sometimes the oil light will also. And to throw off whatever you were thinking it still has this prob with the regulator unpluged (while the bike is not running of course) also still has brake light prob with turn signals unpluged. i pulled back the sheething in the main harness and have spent days looking for burnt wires or bad connections but found nothing the harness is 100% un hacked stock. i even tryed replacing the battery and this led to the bike not starting with the start button, but if i jump power to the trigger wire on the solinoide it fires right up, ignition is not effected. any help woulkd be greatly appreciated. Thanks Brad

Start a new thread so as to not cross confuse the OP with answers inteneded for U