1990 Johnson Evinrude "ES" Cross V 88 thru 115, 150 thru 175, P/N 507874, Page 169Get this manual
1701 10Use micrometer to check piston conditionMake at least two measurements, 90' from each otherMeasure the piston diameter in(6,4 mm) above the bottom edgeRefer to Engine Specifications, Sectionfor piston dimensions The difference between the two piston measurements must not exceed 0.004 in(0,10 mm)
fJ1l 11For new or used ring sets, make the following inspectionsPlace each ring, separately, in its respective boreUse piston to square the ring in the cylinderUse feeler gauge to measure the ring end gap
88 thru 155 Commmodelsthe ring end gap must be within 0.019-0.031 in(0,48-0,79 mm) 175 modelsthe ring end gap must be within 0.020-0.033 in(0,51-0,84 mm)
1721 12Use feeler gauge to check groove side clearance on the
lower, square ringsInstall each square ring on its pistonWith the ring seated in its groove, make several checks around he piston The side clearance must not exceed 0.004 in(0,10 mm)