Bill,
My thoughts were on a slightly different size range. The brushless motors used in the model cars and aeroplanes have quite high short term outputs, some hundreds of watts. They also are designed for high speeds, 10,000 rpm plus. I would have to do a few calculations, but one of these geared up 3 or 4 - 1 coupled to a 15 - 20cc engine would probably work as starter and generator.