1990 Johnson Evinrude "ES" 40 thru 55, P/N 507872, Page 143Get this manual
Cleaning Note Before inspecting or assembling powerhead, all internal components must be perfectly clean and free of contaminants1Remove any carbon accumulation from exhaust port areas2Remove any carbon accumulation from cylinder head combustion chambers3If cylinder walls are glazed from extended use, use medium grit hone to resurface wallsUse slow RPM to achieve strong "crosshatch" pattern for best oil retention and ring sealingINotel To avoid piston or cylinder block damage, restore the chamfer to all port edges using ball hone or other suitable tool i gloves when using OMC Gel Seal and Gasket Remover
To avoid personal injury, wear eye protection and rubber
r.jl 4Use OMC Gel Seal and Gasket Remover to remove all traces of gaskets, adhesives, and Gel Seal II from the cylinder block and crankcase5Carefully remove any carbon accumulation from the tops and ring grooves of the pistonsA ring groove cleaning tool can be made by breaking an old ring and grinding an angle on its endDo not damage ring grooves while cleaning 6Thoroughly wash entire cylinder block and crankcase with warm, soapy water to remove all traces of contaminants