Frame cutting

I'm turning my 78 750twin into a bobber. I've seen "Kogging", where they cut the two side backbone supports out. How dangerous is this and is it advisable.

Konging the frame is when you drop the seat rails, then cut the remainder of the rear frame section off behind the shocks...is this what your intending ?

Sounds more like your cutting the 2 frame tubes that run under the tank to the steering head. I've seen guy's do this to run sporty tanks...GUSSET the hell out of it if this is your plan, these old frames flex without cutting tubes out.

that's what I'm planning, I may take an axtra piece and run it undder the backbone or along side, the tank I'm using has a wide enough tunnel.