1996-2005 Suzuki DF40, DF50 Four Stroke Outboard Service Manual, Page 189Get this manual
POWER UNIT 6-46 PISTON Inspect piston for faults, cracks or other damageDamaged or faulty piston(s) should be replaced Piston ring to groove clearance Before checking, piston grooves must be clean, dry and free of carbonFit piston ring into piston groove, and measure clearance between ring and ring groove using thickness gauge09900-20803Thickness gauge Piston ring to groove clearance Standard: st 0.02 0.06 mm (0.001 0.002 in nd 0.02 0.06 mm (0.001 0.002 in Service limitst 0.10 mm (0.004 in nd 0.10 mm (0.004 in If measurement exceeds service limit, replace piston andor piston ringPiston ring groove width Standardst 1.01 1.03 mm (0.040 0.041 in nd 1.01 1.03 mm (0.040 0.041 in Oil 1.51 1.53 mm (0.059 0.060 in Piston ring thickness Standardst 0.97 0.99 mm (0.038 0.039 in nd 0.97 0.99 mm (0.038 0.039 in