Author Topic: 1980 CB125s Total Electrical Failure  (Read 1335 times)

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Offline Connor

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1980 CB125s Total Electrical Failure
« on: June 26, 2014, 06:40:23 PM »
I have a 1980 CB125s with about 600 miles on it. It's the first year that it's really been ridden - it spent most of its life in a showroom.

It had been running great all season up until last week when it stopped idling all of a sudden. Brought it into the shop for a very expensive weekend and they eventually told me it was a condenser which they replaced.  I rode it about ten miles. This morning, when I turned the key there was no power. After some rather lame jiggling of wires near the battery, I tried the key again and it was fine. Started on the first kick, ran great, everything as usual.

About 2 miles later, I hit a pothole and it just died. No electrical whatsoever.

I checked what visible wires I could see but everything is in such great condition that I can't believe it's a short, but of course you never know with a 35-year old bike.

My gut says it's a loose connector since it happened after a big bump, but I don't know very much about electrical systems. Does anyone have any ideas where I should start to troubleshoot this problem?

Offline Connor

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Re: 1980 CB125s Total Electrical Failure
« Reply #1 on: June 26, 2014, 07:09:24 PM »
I should have mentioned in the OP - those were the first things I checked. Battery connectors are rock solid as is the ground to the frame.

Offline Connor

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Re: 1980 CB125s Total Electrical Failure
« Reply #2 on: June 26, 2014, 07:44:38 PM »
My plan is to take the seat off this weekend and do a visual inspection of as much as I can. If I don't find anything, I'm going to get a cheapo multimeter and try your suggestion.

Offline adrianm413

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Re: 1980 CB125s Total Electrical Failure
« Reply #3 on: June 30, 2014, 06:28:51 AM »
Check for continuity at the key with a multimeter. I had the same problem... And I'm embarrassed to admit that it was the negative battery terminal just loose. I spent days looking for a short with my meter


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Offline RJ CB450

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Re: 1980 CB125s Total Electrical Failure
« Reply #4 on: July 02, 2014, 11:56:32 PM »
I just had dealt with a total electrics failure on my bike.  A start/stop dealie.  Was caused by the fusible link cracked.  It still tested across, but when I took it out to check, had corrosion fractured.  Resistance was reading a bit odd past it.  Ie wasnt no resistance.
74 CB450 K7 Supersport, 82 CB650sc Nighthawk, 1982 CBX 1000, 2015 Tiger XCx.... And some ol minibike with a 5hp Briggs.

Offline grcamna2

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Re: 1980 CB125s Total Electrical Failure
« Reply #5 on: July 06, 2014, 08:26:32 PM »
I just had dealt with a total electrics failure on my bike.  A start/stop dealie.  Was caused by the fusible link cracked.  It still tested across, but when I took it out to check, had corrosion fractured.  Resistance was reading a bit odd past it.  Ie wasnt no resistance.

If it has one of those small 'one fuse' w/ white plastic,make sure to check the ends/connectors that hold onto the main fuse on both ends...& the pos+ & neg- wire terminals where they connect onto the battery posts,one of them may be cracked almost all the way through
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline Connor

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Re: 1980 CB125s Total Electrical Failure
« Reply #6 on: August 02, 2014, 11:12:34 AM »
It was the fuse. Thanks for the replies!