I have a friend who's been trying to refine such a system for a few years now. He says it's really difficult to get around the oxygen sensor thing. At one point he was getting WORSE mileage because the sensor thought the engine was running too lean. He says (and I agree) it would be soooooo much easier to do on a pre-computer car with points and condenser and a carb and such. I would love to do something like that on my bike but it takes a lot of amperage to generate the hydrogen and our bikes don't have enough electrical power.
