GERRY, BILL - Same drill with spraying water into a running Kohler, the engine will sputter but don't spray enough to make it stall. By the time you've sprayed a pint or so into the engine it's about as clean as it's going to get. And like I suggest, I typically did it as part of a tune-up, so change the plug & oil on a K-series, so about every 150 to 250 hours.
With the engine running 1800 RPM, the piston is coming to top dead center 30 times per second, so every .033333 seconds, not much chance for hard carbon particles to get stuck between the piston & cyl. wall and scratch the cyl. wall, or pieces of broken wire brush bristles to get between the piston & walls either. You may get the exh valve closing on a couple pieces of carbon but that crushes up and blows away quickly. The inertia of the bits of carbon on top of the piston throws them up and into the air stream blowing out the exh valve as soon as they pop free.
I ran my old K241 1400 hours without ever removing the head. I retorque'd the head several times in that 1400 hours. Not sure how many hours were on the K301 in the 129 since the Tiny Tach died after about 100 hours in 1-1/2 yrs. But it had to have been 600-800 hrs. by the time I sold it.
It may seem like spraying water into a running engine would damage it, but just think how much water a boat engine eats on rough water and many performance boats have exposed carb inlets, no filter at all.
RICK - So you'll inject water or WWF into a $15,000 Duramax engine... but not a $500 Kohler? O-K... Water injection kits were made and sold by a lot of aftermarket co's in the 1970's & early 1980's to stop detonation when unleaded gas and the early vacuum controlled pollution controls first came out.
About a year ago when I was watching an ep. of NRPA Tractor Pulling on RFD-TV, Ashley Corzine interviewed a Super-Stock diesel puller running a D-21 Allis. He said he burns three gallons of diesel fuel during a pull... and "Burns" TEN gallons of water. He injected water between each of the three stages of turbo-charging, plus had a water injector aimed down each of the six intake ports of the cyl. head to keep combustion temps in control.