Electrical Draw Issues - Bad Rectifier?

Hi Everyone,

This is my first post, so please let me know if I'm posting in the wrong place. I'm having some issues and could really use some help.

First off, I was recently gifted a 1980 KZ750g from a buddy. The bike hadn't been started in about a year and needed a new battery, so I ordered one and sent it to my buddy's house so he could try and start it up before I was able to come pick the bike up. Turns out I ordered the wrong battery for the bike, with the terminals on the new battery being backwards from the old battery.... You can probably see where this is going. Without thinking, my buddy tried to hook the new battery up and crossed the terminals. (I know. He's dumb. But he also is giving me a free bike so I can't really be too mad).

After he realized his mistake, and mine for ordering the wrong battery, I ordered the right size battery for the bike with the terminals in the right place, but when we went to hook it up, we are getting a very large spark from the negative terminal. Large enough to the point where the negative cable is almost trying to weld itself to the terminal. My first thought is that there is a huge draw somewhere. I've spent about a week going through all the wiring and cannot find any spot with any frayed wiring or exposed wire touching the frame. I've used a diagram for the bike to go through with a multimeter and thus far haven't found any continuity issues. (Full disclosure: I am okay at general maintenance stuff and doing minor repairs, but electrical issues has always been overwhelming for me).

I had another thought that maybe when my buddy crossed the terminals, he blew the fuses. I checked the fuses with a meter and they are fine. I have figured out that if I disconnect the Voltage Regulator/Rectifier I don't get any spark when trying to connect the battery. So I know that if theres a short to ground somewhere its on a circuit after the Rectifier, but like I said I can't find any fried or damaged wires anywhere.

Is it possible that I have a bad Regulator/Rectifier that is causing the massive draw? If so, maybe it got damaged when the terminals were crossed?

Any thoughts are appreciated. I'm pulling my hair out trying to figure this thing out.

Part of the message is hidden for the guests. Please log in or register to see it.
Yes, bad rectifier. Dont connect a battery until it is replaced. You might have a combination regulator / rectifier, if so, you need a new reg/rec, rather than a simple rectifier.

Interesting symptom. Wondering did replacing the Regulator/Rectifier fix the problem? I ask because when you mentioned the negative cable is almost trying to weld itself to the terminal. That is a symptom of miswired wires too.

OP has one post. The first here. And he hasn't been back to the forum since posting. Hum...

Nessism wrote: OP has one post. The first here. And he hasn't been back to the forum since posting. Hum...

I have a similar concern about a few other posters. They post questions, the forum posts answers, no follow up from the OP. Then a few days later they start a new post with a completely different problem.

It should be a rule that if you ask for help with a problem you MUST post what the result was. Nothing worse on a forum then not letting people know if a solution was found.
Rick H.