Tohatsu 4 Stroke MFS 2/2.5/3.5A Outboards Service Manual, Page 91Get this manual
Power Unit 17) Inspection of Piston Outer Diameter
1Measure piston outer diameter between points specifiedReplace if it is less than specified valuePiston Outer DiameterStandard value 54.96 mm (2.1638 in) Measuring Point7mm (0.28 in) upward from the bottom of piston skirt Functional Limit54.90 mm (2.1614 in)
18) Inspection of Cylinder Inner Diameter
1Measure cylinder inner diameters (D1D6) at a, and in crank shaft directions (D1, D3 and D5 respectively), and in crank web directions (D2, D4 and D6 respectively)Replace cylinder block if the inner diameters are over specified valueCylinder Inner Diameter (D1D6)Standard value 55.00mm (2.1654in) Functional Limit55.06mm (2.1677in) NoteMeasure at the maximum wear points2Obtain taper through calculation described belowReplace cylinder block if taper is over specified valueTaper LimitD1 D5 (Direction d) D2 D6 (Direction e) Functional Limit0.06 mm (0.0024 in) 3Obtain out-of-roundness through calculation described belowReplace cylinder block if out-of-roundness is over specified valueOut-Of-RoundnessD2 D1 (Measuring Point a) D6 D5 (Measuring Point c) Functional Limit0.06 mm (0.0024 in)