2006 Johnson SD 3.5 HP 2 Stroke Outboard Service Manual, PN 5006562, Page 85Get this manual
POWERHEAD INSPECTION Carefully 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 cleaningThoroughly wash entire cylinder block and crankcase with warm, soapy water to remove all traces of contaminants
INSPECTION
Before any inspection process can begin, all internal components must be clean and free of excess oilRefer to CLEANING on p83Visually inspect all internal componentsCheck for unusual wear patterns, scuffing or deterioration of aluminum parts, heat-related discoloration of bearings or bearing surfaces, and broken componentsCheck for cylinder head warpage using piece of bar stock or machinist's straightedge and feeler gauge set
WARNING
To avoid personal injury, wear eye protection and set compressed air pressure at less than 25 psi (172 kPa)