Pistons and piston rings (1) Pistons Inspect each piston for any abnormal wear of its sliding surface, for cracks at the crown and for evidence of melting or fusion. Examine the ring grooves for stepped wear and sloped wear. Replace pistons found in bad condition. (2) Measure the outside diameter of piston in two direc- tions perpendicular to each other. If the diameter exceeds the service limit, replace the piston. Specifications Unit: mm (in.) -22- Item Standard Service limit Diameter (at skirt) Standard 83.90 (3.3031) -0.2 (-0.008) 0.25 (0.0098) oversize 0.50 (0.0197) oversize 84.15 (3.3130) 84.40 (3.3228) 0.75 (0.0295) oversize 84.65 (3.3327)