Thanks for the replies.
I have no idea of the weight. I have to take the wheels of the trike to fit it in the shed, I can lift the frame without the wheels including the shock. It is starting to feel heavy though, it is not meant as a light weight thing. This probably going to get abused so the bigger the better.
I still have the goped project sidelined. I was working with a frame builder but he was taking so long, so I started the trike. I am going to now weld up my own scooter frame, once the trike frame is out for powder coat. I also have a few other projects in the sideline.
I am not really sure if I can help you much with the seat. It's probably not going to be the most comfortable. I will probably change things as I go along. I like to make things anyway to progress and then come back to them if they cause an issue later. At the moment the seat I am happy with, but I can't guarantee it will be the final seat.
Since I had the steering completed, I have been focusing now on getting the drive system on the scooter. I started with the pedal side as I already know where the front pedals are this will be the datum for my rear cassette and an ideal place to start.
I had a handy new 7 gear free wheel from a previous project. The thread on it was something particularly awkward, being a 35mm 24tpi thread. Had to machine a small weld on hub. Wasn't going to even bother looking for a die, just screw cut the thread on the lathe.
I then bored the hub to 20mm. Slid a shaft through and welded. I really filled it up with weld, which enable me to nicely machine it back again. Can't tell it was ever 2 pieces.
The idea of the drive system is the pedals run to a shaft behind the back of the seat. On one side is the free wheel on the other the sprocket for the rear wheel. In the middle between the two pillow blocks will be the pulley for the motor to drive off. The sprocket and pulley will be use taper lock bushes, so I got a couple key ways to machine on the shaft yet. I needed to use the shaft for alignment so will machine them later.
Here is a few pictures of where I am at.