Tohatsu 4 Stroke MFS 2/2.5/3.5A Outboards Service Manual, Page 92Get this manual
20) Inspection of Piston Ring Side Clearance 1Measure piston ring side clearanceReplace piston and piston rings as set if the clearance is over specified valuePiston Ring Side ClearanceTop Ring0.040.08mm (0.00160.0031 in) Second Ring0.030.07mm (0.00120.0028 in) Oil Ring0.050.15mm (0.00200.0059 in) Functional Limit Top Ring0.10 mm (0.0039 in) Second Ring0.09 mm (0.0035 in) Oil Ring0.17 mm (0.0067 in)
21) Inspection of Piston Rings