Thanks for your feedback, Ron! I see you were trying to use the pocketbike's outer housing to mount the stock GEBE drive pulley. Most of what I'm trying to use is on the BMP friction drive kit:
BICYCLE ENGINE PARTS, MOTORIZED BICYCLE PARTS
I'm using everything in the BMP kit except the friction roller. An HTD drive pulley similar to GEBE's pulley will replace the friction roller on the shaft. If I find a pulley with a 1/2" bore diameter, then absolutely no machine work is necessary.
I have a used Staton wheel with 12g spokes that should work well with this project.