Blown Fuse (?)

I've un-mothballed a `71 Roadster about two months ago from a 12-year sleep... and after getting (most) things straightened out, have had little trouble.

This evening as I was idling (luckily in front of an auto parts store), the red light went momentarily dim, and then everything went dead electrically. At the time I was running with all lights on -- including halogen replacement headlight which was operating just fine.

Naturally it was a blown fuse (30A 32V / Normal Blow 311 3AG type), so diagnosis was simple. So was getting another fuse in the auto parts store which (because I couldn't read the blown fuse specs) I replaced w/ a 20A which I had remembered from some articles back as being suitable as "normal."

Made it home the 3 miles w/o incident and checked all lights/ignition switch cycling, etc, etc when in the garage. No problem.

Other than going through all the wiring entrance/exits to the headlight unit (which I understand is a favorite haunt for insulation breaking/cracking/rubbing), are there other "Classic" failure points in a harness this old that I should go after as a priority?

(I was going out with the troops for Rolling Thunder this weekend, but only if I can convince myself that I won't have to carry a double handful of fuses....or worse.)

Thanks in advance….

MEHAVEY said:

I've un-mothballed a `71 Roadster about two months ago from a 12-year sleep... and after getting (most) things straightened out, have had little trouble.

Other than going through all the wiring entrance/exits to the headlight unit (which I understand is a favorite haunt for insulation breaking/cracking/rubbing), are there other "Classic" failure points in a harness this old that I should go after as a priority?

….

Click to expand...

There is nothing worse than an electrical fault you cannot trace, it invariably is something simple. I would try the ignition and handlebar switch units one of the wires could have came loose, also any area that has flexibility.

Once again, the great headlight shell rat's nest appears to have possibly been the culprit. The Grn/Wht lighting power wire had backed partially out of a broken female bullet connector and (apparently/probably) made contact with the shell's inner metal guide strap. While I saw no obvious burn marks, it was just too exposed not to have been trouble.

That, and while going through the bike front-to-back I wound up taping a series of worn wire insulation cuts -- again mostly entering/in the headlight shell -- and also discovering the rattling noise in the very back was the taillight housing AND the taillight bracket having broken to where only a thin strip of the assembly was holding everything on. [ $$$ ] Also continued cleaning/de-corroding/dilectric greasing connector/light socket that I touched; and cleaned up the handlebar switches/taped the bars underneath them to double insulate.

I just love bringing machines out of hibernation. :evil:

Fingers-crossed for this weekend. :|

Fingers-crossed for this weekend.
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Good luck for the weekend, whereabouts are you?

MEHAVEY said:

Once again, the great headlight shell rat's nest appears to have possibly been the culprit. The Grn/Wht lighting power wire had backed partially out of a broken female bullet connector and (apparently/probably) made contact with the shell's inner metal guide strap. While I saw no obvious burn marks, it was just too exposed not to have been trouble.

That, and while going through the bike front-to-back I wound up taping a series of worn wire insulation cuts -- again mostly entering/in the headlight shell -- and also discovering the rattling noise in the very back was the taillight housing AND the taillight bracket having broken to where only a thin strip of the assembly was holding everything on. [ $$$ ] Also continued cleaning/de-corroding/dilectric greasing connector/light socket that I touched; and cleaned up the handlebar switches/taped the bars underneath them to double insulate.

I just love bringing machines out of hibernation. :evil:

Fingers-crossed for this weekend. :|

Click to expand...

I just went through a myriad of electrical issues on mine, but the last straw was a major wiring failure in the headlight shell. I'll tell you this: Unless I know the specific history of a bike and how old an worn its electrical system is, I will never put it back on the road until I've rewired it. Almost every roadside failure I have had can be traced back to these issues, and it finally took catastrophic failure to make me see the light. Cost money? You bet, but far better than wincing every time I'm 50 miles from home, praying that it will get me back. I also replaced coils, alternator, regulator, and a malfunctioning ignition unit. Now my only electrical worries are if the bike will vibrate a connector loose or something, at least a relatively easy fix.