Trying to fix the POs issues...

[pr1m3]

So I recently picked up a 81 xs400 in non-running condition. Replaced the battery, plugs and oil; thoroughly cleaned the carbs and got it to fire up. Won't idle for shit and will not reliably start. Checked the plugs, no spark. Double check all fuses and battery, fuses wiggle around a lot...then got spark again. Screwed the plugs back in and no spark.

So I started checking out the fuse block and unwrapped some of the electrical tape holding the harness together. What a mess. I don't know if it would be easier to decipher and fix the issues at hand or start from scratch with the bare minimums since this will be a bobber soon. There seems to be a huge loss of power from the battery to the fuse block. I was reading 12.5v at the battery and around 11.3v at the main fuse.

I've included a picture I took. The arrows are things I'm wondering about. Did yamaha use blue electrical tape to splice wires together in the harness? Seems unprofessional, but it was the 80s so I don't know.

Also, correct me if I'm wrong the fuses are: 1) Main 2) Ign 3) whatever the PO rigged up under the left arrow 4) Lights?

The starter button doesn't work on the handlebar so I was jumping the starter solenoid to get it to fire since my foot got sore. I noticed the main circuit was getting quite warm even when I wasn't using the starter...is something grounding out that isn't strong enough to blow the 20A fuse?

Thanks for any help...this thing is driving me nuts.

 

[bcware]

Yamaha does not use electrical tape or splice connections.

I'd convert to a modern blade style fuse block.

That harness is a mess. I can't really see what's going on in just one photo, but that white plastic tube attached to the yellow cap is another fuse.

 

[medmunds]

i just rebuilt one of these.
in your diagram,
1=main, 20Amp red wires
2=headlight, 10Amp red wires/yellow stripe
3=signal, 10Amp brown wires
4=ignition, 10Amp red wires/white stripe


This was the paper guide that was pasted under my old fuse box before i rebuilt it combined with my notes on which wires went to which fuse....it worked for me and got my beast running. good luck!

 

[Sandrew]

Hah, something that still awaits me. Hope you get it figured out.
In my harness there was only on fuse without a fuse box as such and you don't want to know how it was connected..

 

[ThePsuedoMonkey]

Those splicings aren't waterproof!! It looks like your PO tried to revamp the system. I hate trying to decipher wiring issues (being colorblind doesn't help), but I would make a diagram of everything there before getting too far into it. In all likelihood, the PO probably did it to address some issue and you'll end up running into it if you're not prepared. I'd grab a pic of my harness to give you a reference, but the PO on mine did something similar with in-line blade fuses (kind of a mess, but not terrible).

If you're seeing that much of a voltage drop, then I'm sure something is draining the battery. Hopefully you can find it without much trouble. If you have the time and patience to redo all of the wiring, check out Drewpy's thread on it for some protips. I'm guessing that most of the original wiring can be reused for your bobber, but it may be easier to check for issues when you strip it down.

 

[OleDoc]

looks like the po was good at making spaghetti.i would re-wire

 

[OliverB]

Yeah, this is one of the biggest problem areas with our old bikes. Battery acid fumes attack the fuse block and cause the fuse clamps to deteriorate and become brittle. Factor into that the mess some POs have made attempting to "fix" the problem and you can have a real headache. Like others have said, best to totally rewire with either individual weather resistant twist lock fuse holders or a blade type fuse block. Since you plan to simplify the wiring, do it the right way now. I was lucky - my PO left the original fuse block in place for looks but wired in (soldered) individual fuse holders underneath and out of site. Looks stock but is now protected.

 

[branson]

Remove and replace on this issue. Those blue splices are from wal mart. Anyone who wrenches wouldn't buy more than fluids / filters from walmart. Some one attempted to redneck rig that bike into functional condition and failed. My condolences

 

[branson]

Also good luck sir. This shall prove most educational for you

 

[pr1m3]

Thanks for all the helpful advice, looks like I'll be making a new harness while my frame is getting the tail welded up...was hoping I wouldn't have to but oh well.