Hi John,
Sorry for the delay. My wife was diagnosed with lymphoma about the time this thread started. Life has been rather busy as you can imagine.
Here's a PDF of the drawings I prepared for the one I made.
I will email you files you can use with a local machine shop to CNC machine the see saw ad cable flange. You might find it easier than trying to machine manually as I designed it to be machined on a 3 three axis CNC mill. However I did plug in critical dimensions you can use if you want to make it manually.
The sheet metal mount I printed out the drawing to scale, stuck it to a sheet of sheet then cut it to the outline. The software I use automatically works out how much material the bends take up so it should line up perfectly once bent to shape. You will need to weld the flange nut in position as per the drawing.
On the first sheet you'll see a bill of materials table (Its a list of each part required, and if a bought part, the vendor you can buy it from and the part number). Most parts I purchased from McMaster Carr here in the states. They will ship to the UK and are amazing! You can buy pretty much anything from them. Their website is
www.mcmaster.com.
The ball end stud that the rising linkage from the accelarator pedal clips onto is a Holley carb product. You can get a kit for that here
https://www.summitracing.com/parts/hly-20-2/overview/
I used this throttle cable I bought from Amazon over here. I needed to file the nipple down to fit the carb end of the cable.
Amazon.com: Throttle Accelerator Cable ATV Dirt Bikes Fits most ATV Quad Dirt Pit Bike 90cc/110cc/125cc: Automotive
I nipped the other end off and got a ferral from a bike shop that I pressed into the adapter mount to receive the outer cable and hold it at a good angle going into the adapter assembly. The flanged screw clamps the cable end in place on the see saw.
So far I have done a about 2,000 miles with the adaption, some cruising at around 70-80mph and it hasn't given me any trouble.
You can download the STEP files that a machine shop can use here:
Dropbox - Public
And if you want to view them or take measurements from the parts you can use onshape.com Onshape is a browser based 3D CAD program. Its free to sign up and use. It has tutorials that will help you and if you think of an improvement you can make changes to the files through it.
Good luck and feel free to ask questions if I've missed something.
Best,
Steven