1978 Johnson 2HP outboards Service Manual, Page 39Get this manual
5-6 ring landsSee Figure 5-13Check piston for size and rOWldness, using micrometerCorrect sizes are given in Section 2Before installing new piston rings, check gap between ends of ring by placing ring in cylinder bore, then pushing ring down in the bore slightly with the bottom of the piston to square it upSee Figure 5-14Check for ring groove clearance with feeler gageSee Figure 5-15Correct gap and groove clearances are given in Section 2 REASSEMBLY OF POWER HEAD
Proceed slowlyMake no forced assemblies unless press fits are called for, and make no "dry" assembliesBe sure all parts to be assembled are clean and free from dirt and gritA perfectly good cylinder wall, piston, and rings can be ruined in few minutes of operation unless all forms of grit are removed before assemblyWork in clean surroWldings and with reasonably clean handsCoat all bearing surfaces, cylinder wall, etc with clean oil before assemblyWhere the use of oil is specified, we recommend OMC Outboard LubricantIf 'lINOTE