Dave,
In the old days, I'm led to believe they actually added water to the carby
to clean the carbon deposits - that's water in addition to normal fuel.
I have never done this but when you think about it, it does sound logical,
probably get some additional compression as well as the water droplets flash
to steam.
Probably a little 2 stroke oil in there as well wouldn't hurt !
George (down under)

George, I have seen people use a light spray from a garder hose(pipe) to "de-gunk" their piston engines. A balance between clean and hyd-lock is important! Never put in more than the engine can vaporize. (but it can be hard to be sure how much that is.)
Bill Jepson