Electrical/wiring issue - bike completely dead. Please Help!!!!

T6h6o6r

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So I have an '80 special that I've been working on, cleaning up and slowly removing the unnecessary bits. A few weeks back I yanked the stock battery box and replaced it with a little welded electronics box under the seat and was about to install a little bracket to hold the battery, but I've been testing every step of the way, haven't really run into any problems. I have done a lot of shortening of wires that were unnecessarily long and whatnot, but like I said always tested afterwards always okay. So 2 days ago I noticed the wires going to/from my fuse box looked a little worse for ware, so, one pair at a time I cut the ends off and replaced them with brand new connectors. No big deal right? Well, now the bike is completely dead in the water. No power at all. I have been checking continuity like a mad man and everything seems to be connected where it ought to be, I bridged the starter solenoid with a screwdriver and it turned over, the battery is at 12.8-12.9 volts. I'm at a complete loss and about to pull out my hair. Someone please help me out and tell me what/where I should be checking with a multimeter or anything I can try to get power back to my bike. I am so friggin confused and lost I simply don't know what to do from this point. Any help would be just so greatly appreciated, thanks everyone.

P. S. I also unplugged my headlight cause I was painting the bucket... I don't think that should have anything to do with it, but for the sake of being thorough I figured I would add it..
 

jpdevol

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The last bit may end-up being where you find it - glad you included it.
Anyway, one has to work in an ordered fashion or it can be proverbial haystack. With MOV set to volts DC, start at 12ga red wire leading from solenoid - trace it to the connector at the fuse box then trace that red wire to the ignition switch connector in the headlight bucket.
Check for 12VDC to ground each connector along the way.
 

jpdevol

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80_XS650G SCHEMATIC.PNG
 

jpdevol

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Then if that entire red wire checks good to the ign. switch. Turn switch on ands tart on the brown wire from that connector back to the fuse block. Hopefully some sign of life (VDC) will appear by that time. Holler out if ya find it
 

gggGary

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:agree:
I'll just add; failed glass fuses and weak (not making a connection) fuse holders are VERY common on this vintage of Yamahas.
A bad ground strap from battery to frame also popular. Throw a big enough load on it (starter motor) and it might make contact inside while the big load is applied..
 

T6h6o6r

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Okay this is super bizarre. So I checked the red 12g from the starter solenoid to ground, with the ign switch turned on, got zero voltage. However, and this is the strange part, I'm getting 12vdc across the 2 big lugs, both with the ign switch turned off or on?? I even had a spare starter solenoid, so I switched them out, tested for continuity between the 2 lugs and got none, but as soon as i hook it up, it's showing the same 12v across those 2 lugs?!? I am dumbfounded lol. But as for the small wire, I got nothing...
 

gggGary

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The starter is such a huge load that it's about as good as a ground wire, so yeah a meter is going to show 12Volts across the solenoid lugs with the starter connected.
 

T6h6o6r

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I have that exact wiring diagram printed out and been trying to use it to trace the wires, as far as I have been able to tell everything has checked out and has continuity, voltage however is another matter
 

T6h6o6r

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Ok thanks gggary, so that's not anything to be concerned about, I can strike that from my list of possibilities... Now moving forward, need to find out why I have nothing anywhere else...
 

T6h6o6r

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The small red wire on mine is attached to the black wire that leads to the starter, it's not on the red side of the solenoid...
 

gggGary

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The small red wire on mine is attached to the black wire that leads to the starter, it's not on the red side of the solenoid...
Bingo? The SOLID red wire should be on the battery side of the solenoid.
the red/white is connected to the harness, after the ignition switch the blue/white goes to ground in the handlebar starter push button.
 

T6h6o6r

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So strange that it always worked before... At least I thought that's how it was, I suppose when I put everything into the new electrical box and hooked it up I could have hooked it up wrong but I could have sworn I just unhooked it and did it right back up the same... *Shrug* beats me, as long as it works I'm happy. Thank you! I'll report back if I run into any more trouble but as far as I can tell that took car of it!
 

jpdevol

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Whew:D

Edit: The issue was the factory battery lead with 6ga & 12ga splice at solenoid terminal was installed on starter side of solenoid rather than battery side of solenoid (thus not normally powered).
 
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