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Service Bulletin 659, FUSE WIRE/ 1973-74 FL, FLH, FX, FXE, XL AND XLCH
I need to clean this up on my 73 FLH and was wondering what you guys might be doing to correct the issue. Are you staying old school with compliance with the S.B., or did you install a modern inline fuse?
The photo below is of the (a replacement) regulator wire that runs from the regulator, that runs under the frame and up to the battery terminal. The orange wire splice is from the relay under the battery, spliced into the regulator wire that goes direct to the battery terminal. The relay wire should go direct to the terminal with in inline wire fuse per SB659. I also spotted a Tan wire (a few weeks ago) that used to run from the regulator up to the main bundle under the tank. It was fried...this must have been the replacement job.
Yes, I have the 73 FLH wiring diagram and almost have it memorized!
These photos are of the found burned Tan wire that runs up the main wire bundle from the relay up to the tank.
I am slowly replacing some safety issues
Last edited by Bryan Austin; Jun 19, 2026 at 07:09 PM.
You need to post a pic of the rest of the wiring diagram that tells us what the numbers mean...
But the idea of using light gauge wire instead of a circuit breaker seems pretty crazy, even for the 1930`s...
No matter how you wire an electrical system on a motorcycle, there will always be a certain length of wire that is not protected by a fuse or circuit breaker, unless you put a fusible link directly on the battery.
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Service Bulletin 659, FUSE WIRE/ 1973-74 FL, FLH, FX, FXE, XL AND XLCH
