2003 Johnson ST 6/8 HP 4 Stroke Outboards Service Manual, PN 5005471, Page 144Get this manual
POWERHEAD CLEANING
CLEANING
IMPORTANT: Before inspecting or assembling powerhead, all internal components must be perfectly clean and free of contaminantsRemove any carbon accumulation from exhaust port areasRemove any carbon accumulation from cylinder head combustion chambersIf 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 sealing
Carefully remove any carbon accumulation from the tops and ring grooves of the piston ring groove cleaning tool can be made by breaking an old ring and grinding an angle on its end Do not damage ring grooves while cleaningThoroughly wash entire cylinder block and crankcase with warm, soapy water to remove all traces of contaminants
WARNING
To avoid personal injury, wear eye protection and set compressed air pressure at less than 25 psi (172 kPa)
CAUTION