Chrysler 70, 75 and 85 HP Outboard Motors Service Manual OB 3438, Page 135Get this manual
NOTE The taper, or difference between the largest and smallest measurements, must not be more than .002" (0.05 mm) BReplace cylinder block if wear is more than .002" (0.05 mm) or if cylinder is out of roundCIf cylinder is within wear tolerance, but slightly scored, hone with fine stone cylinder honeFigure 34
AMeasure both ends of connecting rods with inside micrometer
Assemble caps on rods, torque to specifications to establish proper diameter10Check pistons as followsAClosely inspect pistons for wear and scoring
The type of damage helps determine the cause: diagonal wear is not normalnew pistons can be damaged quickly in the same wayScoring can be caused by overheatingincorrect ignition timing, incorrect clearances between piston and cylinder and or improper break-in procedure BMeasure piston at right angle to piston pin Check for wear at top land and skirtCMeasure piston micrometerpin bore with an inside
Use low rpm drill with rapid up and down motion to obtain good cross hatch pattern for oil retentionDIf cylinder walls are glazed, break the glaze by honing with medium stone, 220 grit