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Electrical system rebuild

Discussion in 'The Garage' started by windig, May 13, 2020.

  1. windig

    windig XS400 Member

    Hi all,

    Firstly, I'm new to both this site and motorcycle repair in general, so please excuse my probable lack of knowledge. I picked up a 1981 XS400 Special II last week, and it looks to have some pretty severe electrical issues - the insulation on the wiring harness is burned, as are the wires going from the ignition coils to the spark plugs. Both coils showed continuity when testing for resistance so I'm assuming they're busted. Several of the original relays were also burned out or missing, and most of the wiring in general looks questionable. My question was this: being that I'll likely have to rebuild most of the system anyway, should I rewire and order parts based on the original wiring or look for something easier? I saw an earlier thread that had a diagram involving an aftermarket Rick's regulator/rectifier which looked considerably simpler than what the bike originally came with.

    I understand that I have a lot to learn and I'd appreciate any guidance.
  2. markmakeitso

    markmakeitso XS400 Enthusiast

    I'm most of the way through fighting with my friend's XS400 electrical system, and found out a few things on the way.
    -A previous owner replaced the glass fuse holder with modern plastic ones. Didn't do a perfect job, but it was a step in the right direction. Highly recommended.
    -My XS850 project came with a RIck's integrated R/R, which we mounted below the battery box on the 400. I added a different connector so that the 3 AC wires come straight out of the engine into the regulator, eliminating the stock harness for that run. I also removed the 6 pin connector from the R/R and used a new 2 pin connector to run 12 AWG wires straight to battery + and -.
    -We used to have a dying or not restarting when hot issue, and I sliiiightly jumped the gun and threw new Emgo coils on it. Haven't had it act up again yet, but cross fingers.
    -I used a ton of new 6.3mm connectors, which I got in a kit from eBay. Also have a smaller size (2.8mm perhaps?) terminal kit, which is often used inside the headlight. Really handy to just slap a pair of new connectors in when necessary, rather than trying to resuscitate old crusty ones.

    Sounds like you could justify a replacement harness or extensive rewiring. I half wish I had bit the bullet and gone crazy, but wanted to get it on the road fairly quickly.
  3. windig

    windig XS400 Member

    Thanks, that's helpful advice - I just got a replacement stock wiring harness, and the Ricks R/R. I converted all the fuses over as well.
  4. markmakeitso

    markmakeitso XS400 Enthusiast

    Alright, good deal. Sounds like you're on your way already. Should have checked that you have a decent multimeter also, that should have been my first bullet point actually.
  5. windig

    windig XS400 Member

    I do! It's come in handy many times already. Only took new harness, ignition coils, & a regulator/rectifier to get spark. Now on to the carbs...

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