It is possible to swap the 325ccm for a beafier engine, as the engine dont share housing with the gearbox. Its simply a matter of swapping the crankcase and cylinder. Hatz engines have been used. I´m looking at a 406 ccm with electric starter and is also thinking of using a tiny turbocharger. Then it will be bye-bye low milage but probably more fun. Biodiesel is of course primary fuel, made from waste vegatable oil. T/C is available from IHI.