1990 Johnson Evinrude 120 thru 140, 185 thru 225, 300 HP, P/N 507875, Page 194Get this manual
Cleaning JNoteJ 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 cylinder hone to resurface wallsUse slow RPM to achieve strong "crosshatch" pattern for best oil retention and ring sealingTo avoid piston or cylinder block damage, restore the chamfer to all port edges using ball hone or other suitable tool"'" To avoid personal injury, wear eye protection and rubber
ill gloves when using OMC Gel Seal and Gasket Remover
4Use OMC Gel Seal and Gasket Remover to remove all traces of gaskets, adhesives, and Gel Sealllfrom the cylinder block and crankcase 5Carefully remove any carbon accumulation from the tops and ring grooves of the pistonA ring groove cleaning tool can be made by breaking an old ring and grinding an angle on its endDo not damage ring grooves while cleaning6Thoroughly wash entire cylinder block and crankcase with warm, soapy water to remove all traces of contaminants7Air dry cylinder block and crankcaseBlowout all holes and passageways with compressed air