electrical help on '80 GS550

[old_chopper]

I got my carbs clean, new intake boots and o-rings installed, and the bike fired right off.
1-It idled and warmed up, cylinder 4 a little weak.
I have not put new plugs in yet, will next.
Carb could still be suspect too

2-It ran for 4 or 5 minutes then died.
The dash lights come on but starter button won't work.
Jump across solenoid and engine spins over, no start.
With key on and ignition off I have 12 volts on 1 side, 0 on the other.
Turn ignition on and it drops to .3 volts both sides.
Must be a short somewhere? Bike has some wires spliced.

3-I will be losing most of the stock harness (old style chopper project)
I am not interested in chasing the short.
I would like to unhook everything, run 12 volts to the ignition

4-I need to know:
Can I run 12v to the coils direct?
Which wire it is of the 2?
Anything else require 12v to run?
I will not be riding, just checking the engine out. Thanks for all the help already. There is a lot of great reading here!

[old_chopper]

I would also like to know if there is an electronic version of a wiring diagram available.

[BassCliff]

Greetings and Salutations!!

Hi Mr. old_chopper,

It's always best to make sure every electrical connection is clean on the entire wiring harness, from headlight bucket to tail light, including the grounds, fusebox, ignition switch, etc. The coil relay mod is a popular procedure to ensure 12v at the coils. I have a collection of manuals and wiring diagrams on my website. This is known as your "mega-welcome". Please pay particular attention to 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

[mike_of_bbg]

Factory manual with wiring diagram available at bikecliff's site there. Don't miss it - good stuff.

[old_chopper]

I spent the afternoon studying the wiring schematic from the above mentioned website (thanks a ton!) and decided to scrap my factory harness. Found alot of poor previous work. I'm not using 95% of it so I fabbed a new harness using the stock connectors. I currently have a toggle switch and pushbutton starter (temporary). The bike spun over 1000 times better than before and started on the first revolution! With 12.4 volts at the battery I have 11.9 at the coils. I've got around 15 volts from the charging system. Carbs are out of adjustment, no filters yet. It's enough for me to start cutting and welding with confidence I have a good engine. (only 1394 miles)
I have a lot of stock parts for sale. Is there much market for tanks, fenders, gages, wheels, etc?

[BassCliff]

Hi Mr. old_chopper,

Only fourteen hundred miles? Wow! It sounds like the wiring harness you fabbed will work fine. Great work.

Someone posted a simplified wiring diagram a while back, well, about a year and a half ago. I should have kept a copy. I'll see how well the search feature works.

Keep us informed,

Thank you for your indulgence,

BassCliff

[Gyi2os]

Old Chopper,

I feel like i'm leaning towards the same spot you are, i've put 5-10 hours into chasing potential shorts and trying to figure out what the hell is happening in my electrical system. I'm |-| <-This close to scrapping mine and starting fresh.

When you say you scrapped 95% of stock. What did you leave?

When you wired up your coils, did you run the power from the solenoid or direct from the battery?

Any pictures would be great. Right now i'm trying to figure out if i did the Coil Relay Mod correct and can't find anything but a diagram. Real pictures save lives.

-Thanks