Mercury Mariner 4 and 5HP 4-Stroke Outboards Service Shop Manual 1999, Page 144Get this manual
CYLINDER BLOCK AND CRANKCASE
Inspection
Measuring Cylinder Bore
1Measure the cylinder bore diameter "d" at three locations in both and axis2If the cylinder bore is beyond the limits listed in the tables below, it will be necessary to bore or replace the cyli nder blockStandard Value 2.323 in(59.00 mm) 0.020 in(0.50 mm) Oversize 2.343 in(59.50 mm) Out of the Limit If 2.326 in(59.07 mm) or more, cylinder can be rebored to accept oversize piston If 2.345 in(59.57) mm or more, cylinder block needs replacement
Measuring Diameter of the Piston Skirt
Measure diameter of the piston Standard Value 2.321 in(58.96 mm) 0.020 in(0.50 mm) Oversize 2.341 in(59.460 mm)