Someone mentioned somewhere about kicking over a 4 stroke. It's all about gearing, baby! The pedal drive can be configured for maximum starting torque.
How about a derailer type gear setup for the pedal drive? Not many bicycles are stuck with one speed thease days, so why should a modern moped? A continuous variable transmission on the engine side is a no-brainer. Shaft drives would reduce maintainance by eliminating one chain. Alternator and battery so you can cruise at idle in the dark and still have a good strong headlight.
I work for an Aluminum Extruder and it just so happens we push a lot of 6005 and 6061 aluminum tubes, square, rectangular and round. Some day I might just build a protoype "modern" Maxi with an all aluminum frame.