Hydroxy generators for the most part are not stand alone fuel sources. They supplement the engines normal fuel source by making the mix more explosive, faster and cleaner burning. When hydroxy is burned it returns to a water vapor state and cools your engine at the same time it's giving a boost. This allows people to alter the fuel air mixture to lean the engine way past the point where you'd normally burn it up without hydroxy injection.
I bought a very large brown gas generator for my car a couple months back but have yet to install it since our garage needs a good cleaning and doing wiring and work under the hood is unpleasant when temperatures are below freezing outside.
I don't know how practical a hydroxy generator would be on an MB since they usually require at least a 5A draw off a cars electrical system to operate. A 49cc engine would probably require much less gas injection than my 1.8L car though, but wheres the electricity to come from? The pulses from the mag would probably be perfect for breaking water down but it would require some engineering as to not remove that power from the engine spark. You could also compress the gas in a high pressure cylinder for slow release into your engine... however this would be done at your own peril. Hydrogen-Oxygen mix is just a spark away from a large explosion since it's already a perfect mix of fuel and oxidizer.