81 cb750k main fuse/ wiring issues

[Silverfiche]

Hey everyone,

Ok I'm working on a friends cb750. The main fuse was blown so we replaced ... Well attempted to replace it f@&ker blew right away.
Here is my diagnostics so far let's see if anyone else can help.
Rectifier tested : OK
Solenoid is new: tested ok
Silicon rectifier aka diode: old one was bunk replaced
I made a 12volt lamp fuse jumper to try to hunt down my suspected short. Well big bright light until I remove the connector to the sub harness for neutral switch, oil switch, and spark advancers.

So I then tried to put it in gear light goes out. soo I figured maybe my short is at the neutral switch ( as far as I can tell the sub harness is intact). I pulled the clutch to attempt a start and bam lights on again.

Could it be a bad coil?
Btw according to the owner this started with the motor being hard to start , we found that the starter clutch was loose. As in , the bolts holding the clutch together were loose enough to rub on the spark advancer.

That makes me think maybe a bad wind in the starter motor too. Will a starter motor run when hooked direct to 12v if it has a bad wind? Btw the motor runs when connected directly to 12v

Mystery wrapped in an enigma accentuated by many curse words.

Any ideas will help thanks

 

[Silverfiche]

Update:
I may have figured it out after retesting everything and banging my head against a wall for missing this.

The cheapo starter solenoid replacement that my friend got after his issues started is wired backwards for the plug.
Unfortunately as I went to get the soldering iron to fix the spade connector that came apart during disassembly my power went out and didn't come back until just a bit ago.

Testing tomorrow I guess. Good news though in the time I had to kill I went to the bike shop and found a sweet CB350 cafe it followed me home and the GF said I could keep it.

 

[Silverfiche]

Update:
I may have figured it out after retesting everything and banging my head against a wall for missing this.

The cheapo starter solenoid replacement that my friend got after his issues started is wired backwards for the plug.
Unfortunately as I went to get the soldering iron to fix the spade connector that came apart during disassembly my power went out and didn't come back until just a bit ago.

Testing tomorrow I guess. Good news though in the time I had to kill I went to the bike shop and found a sweet CB350 cafe it followed me home and the GF said I could keep it.

Yep the cheapo starter solenoid was wired backwards for my plug a bit of finagling and I got it back together in the proper order. Now it seems the starter clutch needs a rebuild. The dreaded chug chug spinnnnnnnnnn rattle