GS no fire after speedo swap

[mgkoret]

Hello all,
I'm working on a 1979 gs750L and I love it. But, I recently changed the main gauges with a smaller single gauge unit.
I removed the main wiring from the gauge unit. I cut the wires to the fuel gauge and cut a few more to remove the housing.
After this the bike would not fire. I got it to turn over, but no spark. The coils and leads worked fine before the swap so I assume there is a wire that needs to be grounded to finish the circuit, I just need to know what to do to get my bike running again.
I have a wiring diagram and tried to connect the ground wires back together but still nothing. Iv searched the forums but haven't found an answer yet. To pin point the actual wire needed would be great.
Thanks for the help!

[Killer2600]

Do you have power at the coils and ignitor? Thats the first thing to make sure you have.

If only it was as easy just asking someone what is wrong with the bike and them having the exact answer with no testing/checking involved...oh how magical that would be.

[Guest]

Use some jumper wires, and hook the old gauges back up. If it runs, deconstruct it until you find which wires are the problem and then figure out a workaround so it runs again. Think outside of the box, because you might have done something seemingly unrelated that has caused the problem while you were doing this.

[chuck hahn]

Loose plug somewhere????

[BassCliff]

Greetings and Salutations!!!

Hi Mr. mgkoret,

Make sure the orange wire to your coils has 12 volts. Here's your mega-welcome. You'll find lots of resources in the links below.

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Help! Your Bike Won't Start
DON'T DO THESE THINGS
Help! Your Bike Won't Run Well
Oh God! Pods!


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Thank you for your indulgence,

BassCliff

[mgkoret]

With a multimeter set on AC to the highest setting and the positive tester in the +, where should a connect the positive tester to test the voltage to the coil, and do I need to remove the coil or the lead before testing?
I tried re connecting most of the wires from the main unit and still no luck. Still think something isn't being grounded or a short or something. Just want to ride hah

[mgkoret]

The orange wire, with multimeter set to ac 500 and negative grounded to frame, it read 22v and responded when the ignition was engaged.

[Guest]

You need to look up your meter and read the instructions. Coil tests are on the resistance (ohms) scale and voltage tests are on the DC voltage scale preferably in the middle of the scale or whatever is closest to half of what you expect to read (25V would be ideal). Some meters have auto range features. The only tests on the AC scale would be between stator leads in the 100 volt range or higher with the bike running. The instructions will also tell which terminals to plug the leads into for different tests. Instructions are important because meters vary widely in features and controls if you are not familiar with them.

[mgkoret]

I read them. Testers in the ohms neg in the com, meter set to 500 on the ~v. That was how the meter set up instructed. Reached 22v. Sorry for the confusion. I dont do a lot of electrical work.
So if the coils are getting charge, could there be a safety feature on the bike related to the gauge unit that would cause a misfire?

[scrapper]

You didnt hit the kill switch on the right handlebar on accident?

[Guest]

You had to cut more than the wires to the gauges, as you can unplug the gauges and remove them completely from the bike and it will still run. The gauges have zero bearing on the bikes ability to run. You need to trace out what ever else you cut. Sounds like you may have cut the wires going to the right hand control , or the ignition switch.

[mgkoret]

Traced down the issue to a corroded ground wire for the kill switch. Now the bike has power, a new battery, working speedometer, but no fire. Lovely. Doing a spark test in the morning. Then i dont know what next. Carbs maybe