Wow that is a mess :doah: Welcome to the forum :thumbsup: I would just hook a kill switch to the black wire that comes out from under the tank, it goes to the coil and if you ground it it will kill the engine :thumbsup: Hope this helps
You can remove that little copper colored box that has the two wires coming out. You also can remove the wire going into the block through the bolt. I think a 3/8" plug fits that, but can't remember for sure. You only need to use the wire going to the coil for the kill switch. Everything else can go.
The yellow wire with the green stripe thats grounded under the bolt, needs to be connected back to the top of the kill switch. The black wire coming off the top of the block needs to be connected to the bottom of the kill switch. I would do a way with the rest !:wink: