The internals aren't liquid-cooled. The liquid goes around the outside of the engine instead of air to keep it cool. You would have to replace the engine, but that would be a waste of time and money.
I have this 50cc pocket bike and I'm sort of a speed demon so I've been looking into replacing the all the internals with liquid cooled internals. Will it fit? or should I just save the money and buy a liquid cooled pocket bike?