I just bought a KZ750B2. I had it stripped to the frame in a couple of days and then removed the swingarm and cut and ground the rear part of the frame. I have decided to stretch it about 5″. I am going to leave in the double down tubes so that the engine is properly mounted. I will post pictures after the welding is done.
In Calif, a new frame changes your registration and then you need an inspection. Modifing a frame leaves the registration alone. You need to have the headstock and frame numbers, and leaving a significant part of the frame there keeps trouble away.
I own a HD Road King and have owned 20 or so motorcycles in the past. This is my first Kawi, I was impressed with the torque of this twin compared to other bikes. I did have a hard time riding it because I am fat and my knees don’t bend well. After the stretch and relocation of seat and controls, it will be a completely different bike.