Complete wiring for a 1975 XS650

[Yamaha Bobber]

Hi all,

I'm rounding 3 base with my 650 bobber build. This is my first build and now I have a completely rebuilt engine, new headlight/taillight, battery, ect.

I understand the wiring diagrams and believe I will be able to wire everything correctly. My question is what gauge wire should I use for the various components?
- headlight/taillight- 16 gauge?
- main ground off the battery- 6 gauge?
- main power off the battery - 6 gauge?
- coils/stator/rectifier/points/ignition/condenser- 16 gauge?

I am getting ready to buy the supplies and I dont want to run into trouble 3 months down the road and have to re-wire everything due to the wrong gauge wire.

 

[XSLeo]

On the wires going from the battery to the main fuse, fuse to key switch, switch to other fuses, 14 is plenty. From the fuses out to other items 16 is plenty.
On my 75 I use a Ford tractor switch and a 6 fuse block. The key switch came with 14 gauge wires. I have an inline blade type fuse holder. It has pretty heavy wire. I hooked one of these heavy wires to the positive battery post. I then hooked the other wire to one lead on the switch. The other lead of the switch I hooked to the power in bolt on my fuse block.
From each power tap on the fuse box I ran 16 gauge wire to switches and such.
The 16 gauge is plenty for the higher draw items like the ignition and head lights, power to the turn signals and horn. The stock turns draw more than the headlight when they flash. On the lighter draw things like dash lights, tail light. 18 gauge will work.
If you convert lights to LED then you can use even lighter wire. 20 or even 22 gauge wire.
If you are using the e-start then the cables from the battery to the starter should be at least 8 gauge, Heavier cables like 6 or even 4 will carry the current for the starter with less loss. The stock cables are either 10 or 8 gauge. Not really heavy enough.
On my 75 I used 6 gauge cables from the battery positive to the starter relay, from the relay to the starter. I even ran a cable from one of the starter mount bolts to battery negative. This is a ground path with fewer connections than from starter to engine through the mounts to the frame, frame to battery.
I'll post pics of my switch and fuse block.
Leo

 

[XSLeo]

Shopping at an auto salvage yard for battery cables is a good idea. I found several feet of cables for less than $5. Maybe ten feet.
Leo

 

[Yamaha Bobber]

Thank you for the info.

the last engine I wired was for a late 70's chevy big block boat engine. I use 14-16 gauge wire for most of the engine, but 4 gauge from the battery to the starter and 4 gauge to the alternator.

It just seems foreign to me to use such light gauge wire for the main power, but it makes sense because there is less amp-age need for the bike to run.