David Teahay (OP), are you still out there? Briggs and Stratton sells small industrial engines in Nigeria. There are 2 retailers listed in Lagos, maybe others elsewhere. They are 4 stroke engines (so heavier than a 2 stroke of the same power), but they are simple and reliable and require no other gearbox or belt drive. They won't work for a Whing Ding (to heavy), but will work for some other small single-seat aircraft.