Paul, yes it is an accepted practice. If you search the forum you'll find quite a few posts on the subject. Here's a post from forum member Dennis Frisk (dfrisk) from back in April 2012:
" RON - Gerry Ide and I were the ones who suggested spraying water into a warm or hot running engine to decarbon it. Gerry & I are about the same age, both read Hot Rod Magazine back in the 70's. WATER Injection was used to prevent pinging & detonation in high performance car engines with the bad no-lead gas and non-electric pollution controls. As a side benefit it also kept the combustion chambers clean of almost ALL carbon deposits.
Yes, I've done it to several of my old CC's, get them warm, run about 1800-2000 RPM and with the air cleaner cover removed spray water from the tap into the carb with a spray bottle. The engine will miss, sputter, stumble but not die and have people NOT STAND in front of the exhaust outlet from the muffler because tiny and not so tiny pieces of warm/hot carbon will be flying out of the muffler.
It won't clean a combustion chamber as clean as a wire wheel brush on a drill will but it doesn't get fine carbon dust down between the piston & cylinder as bad as a brush will. Also don't have to replace the head gasket. About a quart of water is all you need for a Kohler.
I ran a rebuilt K241 1480 hours and never pulled the head. Cleaned the combustion chamber a couple times with water. "