1997 "EU" Johnson Evinrude 5 thru 15 Four Stroke Service Manual, P/N 507262, Page 178Get this manual
16The difference between your measurements and standard bore dimension is cylinder oversizeRefer to Engine Specifications, Section 1, for dimensionsThe cylinder must not be oversize by more than 0.002 in(0,05 mm)1Note If any cylinder is outside these tolerances, it must be bored
oversizeOne oversize piston is available for this engine 0.030 in(0,762 mm)To determine oversize bore, add 0.030 in(0,762 mm) to the standard boreRefer to Engine Specifications, Section 1It is permissible to have one or more oversize pistons
17Place the top two rings of each piston, separately, in its respective boreUse piston to square the ring in the cylinderUse feeler gauge to measure the ring end gap The ring gap must be within 0.0060.014 in(0,15 0,35 mm)
18Use feeler gauge to check groove side clearance on the top two ringsInstall rings on pistonWith the ring seated in its groove, make several checks around the pistonThe side clearance must not exceed 0.004 in(0,10 mm)19Use machinist's straightedge to check clearance on the top two ringsInstall rings on its pistonWhen checked with the straightedge, there should be enough ring clearance to allow the straightedge to touch the piston on both sides of the ring grooveMake several checks around the pistonIf straightedge does not touch piston, remove the ring and clean ring groove20If the grinding on the sides of the piston is worn smooth in pattern similar to the illustration, replace the piston