Topic: 1980 CB125s Total Electrical Failure

[Connor]

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?

[calj737]

Obvious places to start are the nuts at the battery, and the ground wire from the battery to the frame. These should be tight, clean and rust free. As you describe it, it sounds very much like its "grounding out". You can then also check at the fuse block and the connections there.

It's going to take some investigation work, going through each and every connection until you find the one that's "obviously" loose.

[Connor]

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.

[calj737]

Excellent. So you know a little bit about electrical items after all 

So when it "dies" can you test the voltage available at the coil, the starter, or the battery? Do you have a multimeter by chance?

[Connor]

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.

[adrianm413]

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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[RJ CB450]

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.

[grcamna2]

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

[Connor]

It was the fuse. Thanks for the replies!