1981 Johnson/Evinrude 4HP Outboards Service Manual, Page 49Get this manual
REASSEMBLY OF POWERHEAD Proceed slowlyMake no forced assemblies unless press fits are called forand make no "dry" assembliesBe sure all parts to be assembled are clean and free from dirt and gritPerfectly good cylinder walls, pistons, and rings can be ruined in few minutes of operation unless all forms of grit are removed before assemblyWork in clean surroundings and with reasonably clean handsCoat all bearing surfaces, cylinder walls, etc with clean oil before assemblyWhen the use of "oil" is specified, we recommend 50 :1 outboard lubricantFigure 5-14Cleaning Piston Ring Groove
Always use new gaskets throughout when reassembling the powerheadApply OMC Gasket Sealing Compound lightly to both sides of cylinder head gasket and to outer diameter of crankshaft sealDo not use sealer if so stated on the gasket
Before installing new piston rings, check gap between ends of ring by placing ring in its respective cylinder bore, then pushing ring down in the bore slightly with the bottom of the piston to square it upSee Figure 5-15Check for ring groove clearance with feeler gageSee Figure 5-16Correct gap and groove clearances are given in Section 2