Is this normal?
#2

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Depending upon the fuel used and the mixture setting, you can most certainly get carbon buildup on the top of the piston and inside the cylinder head. Fuels containing castor oil will especially show this. Running very rich over time with an all-castor (or ostly castor) fuel will give you quite a buildup. If the carbon is hard, shiny black, then it means your engine's been run a bit on the hot side.



