I'm just running in my Evo 10cc gasser engine in, now on about the 4th tank of fuel and I'm still getting a huge amount of black gunk from the exhaust, which in turn turns the fuel in the tank black, almost instantly, via the muffler pressure pipe. The mixture is right at 20:1, I'm using fully synthetic two stroke, and the mixture seams ok as it's running pretty well. It's costing me a fortune in wipes and it's not got off the ground yet.
Any suggestions, gratefully accepted.