76 CB750k Electrical Probems

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76 CB750k Electrical Probems

Timrek
Hi,

I have a bit of a parts bin bike but it is mine now and I am excited to get it going. It is a 1976 cb750K6 from the front forks back. The front end is off of a 1979 cb750F super sport from all that I can tell.

I am new to the site and to owning and working on motorcycles. I am ok at most mechanical things but I am stumped at this electrical problem I am having.

I bought an old bike that has been in storage since 86. I have the carbs all cleaned up and every thing back on the bike. I got a new battery and put it in about a week ago. I had to reconnect all the turn signals and start button. When I first put in the battery I had a few wires in the wrong place but with in 15 minutes I had all the turn signals, headlight and start button working. I took out the battery because I was still getting some parts ready to go back on.

Yesterday I put the battery back in and tried to get the horn working. No luck with the horn. But the turn signals would not blink at all. Only the front ones would come on and the back ones would not work at all, but the starter still worked.

Today went to put everything in and put some gas in to try and start it and there is NOTHING going on in the electrical department. No lights, no starter nothing.

So, any ideas or help would be really appreciated.
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Re: 76 CB750k Electrical Probems

Re-run
Administrator
Well first off, get the manual we have here and the wiring diagram. Trace all the connections and make sure the contacts and connectors are all clean. Clean the fuse holders too and probably new fuses. A good possibility is that the a fuse could have been blown if the wiring is wrong for the horn.
The ride IS the adventure. The destination is just to get gas!
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Re: 76 CB750k Electrical Probems

bluelabel1927
In reply to this post by Timrek
I 2nd that.  electrical probs are not magical they are methodical.  Something is dirty, blown or disconnected.  I tore the whole harness outta my bike because I have about zero faith in wiring older than I am.  HondaChopper.com has a REALLY good simplified wiring diagram.  I used it and my bike works like a champ.  

I used the harbor freight "wiring store house" 20bucks and heat shrink 6bucks, for a fuse block I buy the  discount auto 6 blade terminal block 8 bucks, and bullet connecters 6 bucks.  

SO for less than fifty bones you can re wire and have a something you fully understand and works great. Very reliable little unit and no more sketchy glass shizzle to fizzle out. It is easy, and then you KNOW every wire to every thing, and BOOM your gremlins are defeated,   Good luck man if your deal persists holler and I can coach you through.  i have wired a half dozen bikes or so from scratch, and this one is a piece of cake.  
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Re: 76 CB750k Electrical Probems

Timrek
Thanks guys.

I do have the Clymer manual and a pdf version of the shop manual a good battery and digital meter. The problem is that I am not sure how to use the digital meter to test circuits. Can any one give me a crash course?

Beyond puling in the yellow wire to the yellow wire and the green to the green I know very little about working through electrical problems.

I did a lot of work to get the turn signals, and handle bar start switch hooked up to the right places, at least for me it was a lot of work. The first time I put the battery in and turned the key on the bike all of that was working good. Then the next time I put it in, even before I tried hooking up the horn, things were not working right. I did not do anything to the electrical system in between those two times.

The fuses all look good but I will clean the contacts and pick up some new fuses. Eventually I would like to put in a new fuse box that uses the blade type fuses but I just want to get the thing running right now.
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Re: 76 CB750k Electrical Probems

bluelabel1927
In reply to this post by Timrek
Use the ohm sign on

your meter
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Re: 76 CB750k Electrical Probems

Timrek
It is finally running!!!

I sprayed a some electrical cleaner in the igniton switch. That seemed to work. The turn signals still not working but I think that is the relay. Any one know how to test them?
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Re: 76 CB750k Electrical Probems

fpcb750er
It's a very cheap relay, just take it off, and take it to any autoparts store and ask them to match it.  The local store I go to brought out a cardboard box of relays and said "here ya go, you match it"... $3.50 plus tax.
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Re: 76 CB750k Electrical Probems

Re-run
Administrator
If you can, get an electronic one. That way it does not rely on having ballast to operate correctly. An electrical flasher is the way to go. You can also put on led turn lights in the future then. Thats where ballast comes in.
The ride IS the adventure. The destination is just to get gas!