Re: Lets think this through.....
Probably not the greatest of ideas to be honest but possible.
Better would be to get hold of two Lohmann engines (2 x 18cc) and make them into a 36cc twin. They are compression ignition engines that will run on various different things- diesel/petrol/paraffin mix seems to be the norm..
They can be found often on the german ebay site - make very very sure they are complete...
"....Look, no pedals... *thud*..." The mating call of the motorized-biker.
"RetroEagle" - 32cc Two-Stroke, Piped. 35mph on #13 gear. Reversed stem with springer fork.