Series 3--Based on BMW K100. This is one fast bike but has a number of complications that make it a difficult build. It has fuel injection which makes it run great, but requires some special plumbing in the fuel system.
Front view 
Side view
BMW !
Series 2--Based on Honda Goldwing. A lot easier build but with the issues of (4) carburators. A lot smoother and quieter than the BMW and only marginally less power and fuel economy.
Sampling of constructrion photos
The assembly manual has well over 200 photos that detail every aspect of the build.
In the manual we start with the initial strip-down of the bike and the welding of the front frame member to the VW front end. This is very important as it sets the frame alignment and serves as the base of the seating area.
We weld a section forward of the VW
axle that will serve as support for the radiator and as a base for the
gas, clutch and brake pedals. The photo to the right shows the
framework of the seating area, that will eventually be covered with
plywood slats.
A framework is built around the
structure to act as windshield and roof. The same is done to the
rear to prevent wind turbulence and shelter the engine.
Sheet aluminum is bent to cover the body structure. The interior is padded and covered with vinyl.