'82 CB750K lifetime charging system problems, help!

[Chuck78]

My buddy is constantly asking me to help him rebuild his electrical system on his 82 CB750. I think it's a K model. The bike has only 7000 miles. He has had if for 8+ years and has barely gotten to ride it, as the charging system has failed on it maybe 3 times or more now. He has had it repaired by highly regarded mechanics that say "yep, we got it fixed right this time!"

He said he has a box of charging system parts that cost him over $200 a pop each time the bike stops charging. He was thinking that there was some problem in the wiring harness somewhere, and I thought maybe just rewiring it from scratch would be the ticket, and testing all the switches and electrical components. The only thing he could find wrong with the wiring harness from a visual standpoint was all the holes poked in the insulation from people stabbing their test lights and continuity testers into the insulation.

He has said that literally the bike runs for about 100 miles and then it may blow a fuse or two, and after replacing, shortly thereafter the charging system just fries itself. He has read about some other people having the same exact problem, but no one seems to have an answer. Seems as if this bike has had this problem most of it's life, as it looks like it's never been ridden even, almost like new.

I have some ideas, but I wanted to pick everyone's brain about what to look for or how to approach this to do better than the last mechanics.

Thanks

 

[Chuck78]

I will get more info from him, but I believe it was the main fuse that kept blowing each time before the system went totally out. I would want to probably run the bike off of a fully charged good battery first thing (with charging system disconnected, I rode a bike once for 10 miles off battery and chain-severed stator wires), and test the output of the stator like the GS stator papers tell me, not sure if the ohmage and the output voltage would vary much from a GS.

Secondly, from people swapping them onto GS's, I know some Honda's have a (brown?) voltage sensing wire on the Regulator/Rectifier. I wonder if there is a bad connection here, or a problem with this? If that wire connection had corrosion, bad contact, pinched wire, etc, it could likely be overcharging the system, but that would potentially blow light bulb filaments and wreak other havoc, right? Something shorting to ground or low voltage would cause higher amp draws to blow fuses. Higher voltage would mean electrical devices would draw less amperage.

I was also suspicious of the ignitor, as I suspect it has a massive antiquated ignitor box like my buddy's 82 GS1100 w/850 engine. That thing started going out and working intermittently, failing 30 year old resistors, transistors, and diodes worried me from the start. I've not ever known ignition coils to fail and still run the bike but short out to ground, so I didn't suspect that. I figured it has to be something with the R-R wiring, or some other problem with the bike's wiring harness. I think I will try and fit on a Shindengen Series R-R like I did on mine, or at least a Shindengen MOSFET R-R and ditch the Honda stuff. Test the stator, sounds blown... Is there any sort of oil sprayer or oil bath cooling on the DOHC Honda CB engines???? Inspecting the stator to see if it looks burnt would be helpful.
I figured then I might get the bike back up and running with most of the wiring unhooked, running only the ignition and charging system really. Use hand signals like my chopper/cafe buddies do with indicators deleted. Go for a few good long rides with cell phone and AAA card in hand, see how it does, then maybe replace the individual fuses with lower amp rated fuses to see if any are close to blowing under normal conditions with the lighting hooked up.

Honestly it sounds to me like a perfect bike to totally strip down and do a custom sorta cafe racer out of it, although I despise the cafe seat look and some of the stereotypical cafe-look treatments. full seat like the early CB360's, superbike/drag/clubman bars or clip-ons, find some old used Goldwing spoked wheels, aftermarket mufflers if not 4-1. barebones gauge cluster... perfect!