BTW that wire that was hot to the touch is the same one that melted on my own GS. It's undersized for the purpose anyway so it's at risk but in my case what caused the meltdown was heat from the regulator/rectifier. Anyway I rewired with 10ga ground wire and even rerouted a bunch of grounds and overall improved the wiring since I had a number of melted and destroyed wires, but to eliminate the root cause required me to throw away the stock reg/rect and replace it with a MOSFET unit.

Anyway, I was going to write long about this but it doesn't matter. I still think you need to replace the reg/rect and would be smart to replace most of those wires. The 16-18ga wiring used in the GS is just too small for this anyway, I used 10ga when I redid my ground wiring. I would bet the reg/rect is on its last legs and I'd advise you find a way to get a MOSFET unit in there, although it an be sort of expensive to make this plug and play. You can read more about my saga over in the projects thread.

Quote from: Kiwingenuity on December 09, 2018, 05:07:09 PM
...CUT...

Thank you but i don't understand electricity that well 

The link you posted is the same guide i'm following to find the problem

I changed the regulator with an sh775 mosfet unit and now i have over 15v on the battery, even over 16 with the revs up. isn't this way too much?
Turning on the headlight it goes down to the usual 12.8 and less.

I don't know what to do. I cut the wires from my oem regulator to wire the mosfet unit so i can't even put the old one back in.

I'm not going to go back and re-read all of this so it might not be 100% or even 50% relevant, but...

with everything you've done, the fact that the voltage goes down when you "turn on the headlight" indicates your wiring and/or connectors are corroded. There's no way to know exactly which one besides inch by inch chasing down every single wire following the wiring diagram and verify the connections are not corroded, replace (likely) as necessary, and probably also replace a lot of that wiring. This is not a horrible job, but it sounds like you need to learn some new skills or make a friend.

If the charge voltage is only 12.8 the battery won't charge effectively. Replacing parts like the battery and reg/rect is useless until you absolutely verify the wiring and connectors. When I say wiring and connectors I mean every single wire in the bike and every single connector. This is a cumulative problem, not likely just a single point of failure. Its like out of 20 (?) connectors in the bike, all of them are corroded to some degree, and the corrosion from the connector extends down the wiring inside the insulation for some length usually a couple of inches for each wire, so much so that nearly rebuilding the wiring harness is probably the quickest and easiest way to fix it.