1980 Johnson 4HP Service Manual, Page 58Get this manual
performance of the engineBefore reinstalling the pistons, break the glaze using fine cylinder honeUse low drill with rapid up good crossand down movement to obtain hatch pattern for good oil retentionUse hone with medium stone (220 grit) GASKET SURFACES all traces of dried cemen from gasket Gel Seal and Gasket surfaces, using No390928Check all gasket faces for flatnessUnder certain conditionsgasket faces warp spring, particularly where thin flanges employed and sections subject to tempe rature changes830315
Figure 5-1
Surfacing Cyinder Head
PISTONS Check the pistons for roundness, excessive shirt wear, and scoringThe piston skirts must perfectly round and unscratched to prevent the entry of exhaust gases into the crankcase deposits chamberCarefully from inside piston headInspect the ring accumulationexcessive grooves for wear, damage to the ring groovesCarefully scrape from the ring grooves, making clinging to the bottom and certain that sides of the grooves has thoroughly removed without scratching otherwise damtool for cleaning the ring aging the groovesmade from broken ring with grooves sharpened edgemust taken not to damage the ring landsSee Figure 5-14Clean from top of piston, taking not to alter piston deflectorCheck piston for size and micrometerCorrect sizes roundness, using given in Section 2If out of round than 0.0025" (0.064 replace piston