2009-2010 Suzuki DF70A DF80A DF90A Outboard Service Manual, Page 162Get this manual
1D-51 Power Unit Mechanical: Cylinder Bore Inspect cylinder walls for scratches, roughness, or ridges which indicate excessive wearIf cylinder bore is very rough, deeply scratched or ridged, bore cylinder and use oversize pistonCylinder Bore Wear (Difference) Using telescoping gauge (1), measure cylinder bore in both axial (vertical line, following crankshaft) and transverse (horizontal line across crankshaft) directions at two positions as shown in figureNOTE Purchase commercially available telescoping gauge for this measurement"a"
Piston to Cylinder Clearance 1) Measure the piston diameter at point 13 mm (0.512 in above the piston skirt at right angle to the piston pin boreSpecial tool (A): 0990020203 (Micrometer (50 75 mm)) Piston skirt diameter Standard: 74.970 74.990 mm (2.9516 2.9524 in
Check the following: Difference between measurements at the two positions (taper) Difference between axial and transverse measurement (out-of-round)If measurement exceeds service limit, bore or replace cylinderCylinder bore wear (difference) Service limit: 0.10 mm (0.039 in