I have and 40 el knucklehead has been wired for twelve volt with regulator was taken apart when i got it. What I need to know is does the one wire from the regulator go to and key hot or strait to battery.

I wouldn't mess with electric stuff. All you need is a shortage and you are screwed.

You need to have one wire goes directly to your battery pos or a breaker that is hooked to the battery pos.

Thats the way I had hooked up but it arced when i hooked up the battery. I would not think it would arc unless the motor was running

I am confused. It arced when the motor was running? the battery?

Just a quick question, are you sure the battery is good? Have you checked that?

Sounds to me that you have bad voltage regulator.

are you using Solid State voltage regulator? what kind of regulator is it?

You have to make sure you got the correct voltage regulator. You may need to dig into some old books to find out.

More information about the regulator is needed

Thanks for the info found out what I needed to know locally

Will be nice if you share it with us.

I have and mechanical type regulator and the contacts corroded there fore causing it to arc when attempting to hook up