New Harness issues (wires went up in smoke)

I am terribly frustrated with this project and would really appreciate some input from this board. I rebuilt my harness according to the diagram provided by loudvlx (below). Bike is a 77' 650B1. I used 16g throughout except for the starter cables I used 10g. I did not include the second optional 20amp fuse. I used heat shrink tubing everywhere and could not find any uninsulated wire. I hooked up my battery and turned the key, but did not start the bike, and a few wires instantly went up in smoke. From what I can tell only 3 wires burned. 1) the white wire coming off the voltage regulator running to the main power line 2) the black-black/yellow running from the rectifier to the voltage regulator. 3) and the main power line up to the 20amp fuse.

I have no idea what the problem is because i used this same diagram on the bike to get it running a few weeks ago. This new harness was just an attempt to clean up the connections and fully insulate everything.

My take on this is, at least 8 AWG (American Wire Gauge)should be used for the cable from the battery Positive(+) terminal to the starter motor through the starter solenoid. If you've got a cold engine, the outside temp is 50F or so, and high compression, the 10 AWG wire will be too small,and possibly melt.

Welding cable would be another choice, but 6 AWG will be better than 8 AWG for better current flow.

NickMac wrote: I am terribly frustrated with this project and would really appreciate some input from this board. I rebuilt my harness according to the diagram provided by loudvlx (below). Bike is a 77' 650B1. I used 16g throughout except for the starter cables I used 10g. I did not include the second optional 20amp fuse. I used heat shrink tubing everywhere and could not find any uninsulated wire. I hooked up my battery and turned the key, but did not start the bike, and a few wires instantly went up in smoke. From what I can tell only 3 wires burned. 1) the white wire coming off the voltage regulator running to the main power line 2) the black-black/yellow running from the rectifier to the voltage regulator. 3) and the main power line up to the 20amp fuse.

I have no idea what the problem is because i used this same diagram on the bike to get it running a few weeks ago. This new harness was just an attempt to clean up the connections and fully insulate everything.

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The white wire from the R/Zr to the battery/ Starter solenoid connection,needs to be 10 gauge. This is the charging wire to handle the 20 amps the bikes charging system will make. Also the Wire leading from the battery to the Ignition switch with the 20 amp fuse in the diagram needs to be at least 10 gauge anyway. This is the supply power for the bikes electrical, except the Starter Motor. The Starter Motor is a heavy Amperage circuit, which is the battery cables.
With the wires you melted by just switching the bike to ON, and Not trying to start it. I would think you could have a bad Diode in the R/R assy. Or you have something, like the ignition coils shorted, although that should have blown the 20 amp fuse. The only thing on the diagram, not fused is the R/R to the battery/ starter solenoid post. If the diode is bad it will do exactly what you experienced, melt the wires on that circuit.