Boat Soat gets the soot out...
I use simple 'Boat Soap' and the black soot washes right off. Never a problem.My engine is a 1 cylander diesel Yanmar.Not much tuning you can do to that puppy.It's my understanding that much of the "soot" is from unburned diesel at time of engine shut off. But, even after cranking the rpm (in neutral) right before shut down (as reccomended in the owners manual), I still get a bit of smoke, a small black skid on the water, and after several outings a black film on the bottom of the transom.I haven't dared to run her over 3000rpm, and usually settle between 2200 and 2500rpm.Bottom is race ready. If anyone has any ideas on how to eliminate this in the single-hammer Yanmars, I'm all ears!Kevin in VT