Author Topic: Electrical problem  (Read 574 times)

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Offline snakeatmaus

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Electrical problem
« on: September 08, 2015, 08:48:40 AM »
Hi guys! First time posting on here, long time reading info from your page though, anyways, onto the issue.

I recently got a 1978 CB550K that has clearly been slightly altered by a previous owner. It should also be stated that my dad originally bought this bike, and then had let it sit for over a decade. I will post a pic when I get home. I have been taking the last 2 months or so just to clean things up and check that everything still moves where it should, and stays put where it should. Long story short, after checking that everything seems to be fine (visually), I put new oil in it, got a new battery, and tried to start it. (and yes, before anyone asks I did follow the right steps and checking the required items as outlined here on the forum for trying to start/resurrect an old bike)

Let me be clear, I wanted To start it, but I never got that far. When I touched the second battery terminal with the positive lead, therefore completing the circuit, the tail lights and the neutral lights came on, but then it immediately began to smoke. I got it disconnected as quick as possible, but the damage was disheartening to say the least. I have never tackled wiring before so this is very intimidating to me. When I looked the wiring over later the next day I found that a green wire, starting at the regulator, passing through a couple connectors and terminating at the left ignition coil (looks to be the ground I think, again, will post pics later today) had melted through its insulation and through the external wire wrapping. It was completely exposed!

I've never run into this sort of thing before, it's a vintage bike that has sentimental meaning to me, and my dad. We would love to be able to hear that engine purr before the cold hits here (NE Wisconsin). I will have additional maintenance to do over winter, so in reality there is no rush, but any help would be great! Thanks guys!
« Last Edit: September 08, 2015, 08:56:25 AM by snakeatmaus »

Offline Steve F

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Re: Electrical problem
« Reply #1 on: September 08, 2015, 09:45:06 AM »
First off, welcome to the forum and you'll be able to get just about anything fixed with the great advice available from the fine folk that frequent here!
It sounds to me like you have reversed the polarity when you hooked things up at the battery.  Some batteries have the (+) and (-) at the opposite ends of what you need and can easily be hooked up that way without even knowing it.
Hope you get it figured out and fixed easily, but once the polarity has been reversed, that usually means a new recitifier assembly and maybe a new voltage regulator too.
Steve F

Offline Mantree

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Re: Electrical problem
« Reply #2 on: September 08, 2015, 10:34:12 AM »
Take this as a good opportunity to update the bike with a new regulator and rectifier while you are in it you can swap the fuse block for a new atc block.  These bikes are simple and I actually enjoy rewiring them because they are simple but you can buy a all new harness if you need to

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Offline snakeatmaus

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Re: Electrical problem
« Reply #3 on: September 08, 2015, 11:01:21 AM »
Thanks for the reply, and the welcome guys.

Steve F I have found tons of sources for this part, but I don't know which sites to trust, or what I should pay for a voltage regulator.

Any help?

Second, Mantree, I would like to re-wire it, but I have no practical knowledge of how to do this. Is it challenging? Is there a step by step out there, or a good place to start at least?

Offline Mantree

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Re: Electrical problem
« Reply #4 on: September 08, 2015, 11:54:15 AM »
If you can find a wiring harness for sale then it is a easy to pull the old one out and tie a new one in hondaman sells direct swap atc fuse blocks and while you are at it swap in a electric flasher and go to led signals (your charging system will thank you) if you feel confedint in your ability you can run a simple wireing system meant nt for a chopper

This is a wireing diagram that I made for my chopped cb750 and looking at your wireing diagram it would work for you I installed a 30 amp relay to take the load off the ignition and I am running a hotrod ignition switch.  So my starter is run through it just look up cb750 chopper wiring and you will find hundreds everything from all lights to just head and break lights

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Offline Mantree

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Re: Electrical problem
« Reply #5 on: September 10, 2015, 02:53:45 AM »

Offline switchum

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Re: Electrical problem
« Reply #6 on: September 10, 2015, 03:38:33 AM »
For  a regulator /rectifier,  I recommend Oregon Motorcycle Parts. 

http://www.oregonmotorcycleparts.com/rectifiers3p.html