7. CYLINDER/PISTON DINK50/ 125
SPECIFICATIONS(DINK 50) Unit: mm (in)
Item Standard Service Limit
I.D. 39.0039.01 (1.5601.5604) 39.1(1.564)
Warpage 0.05 (0.002)
Cylinder
Cylindricity 0.05 (0.002)
True roundness 0.05 (0.002)
Ring-to-groove Top 0.0150.055 (0.0060.002) 0.09 (0.0036)
clearance Second 0.0150.055(0.0060.002) 0.09 (0.0036)
Top 0.100.3 (0.0040.012) 0.5 (0.02)
Piston, Ring end gap Second 0.100.3 (0.0040.012) 0.5 (0.02)
piston ring Oil side rail 0.20.7 (0.0080.032)
Piston O.D. 39.98539.995(1.59941.5998) 39.9 (1.596)
Piston O.D. measuring position 9 mm (0.36 in) from bottom of skirt
. Piston-to-cylinder clearance 0.010.04 (0.00040.0016) 0.1 (0.004)
Piston pin hole I.D. 13.00213.008 (0.520080.52032) 13.04 (0.536)
Piston pin O.D 14.99415 (0.599760.6) 14.96 (0.5984)
Piston-to-piston pin clearance 0.0020.014 (0.000080.00056) 0.02 (0.0008)
Connecting rod small end I.D. bore 13.01613.034 (0.520640.52136) 13.06 (0.5224)
TROUBLESHOOTING
· When hard starting or poor performance at low speed occurs, check the crankcase breather for
white smoke. If white smoke is found, it means that the piston rings are worn, stuck or broken.
Compression too low or uneven
compression Excessive smoke from exhaust muffler
· Worn or damaged cylinder and piston rings · Worn or damaged piston rings
· Worn, stuck or broken piston rings · Worn or damaged cylinder and piston
Compression too high Abnormal noisy piston
· Excessive carbon build-up in combustion · Worn cylinder, piston and piston rings
chamber or on piston head · Worn piston pin hole and piston pin
· Incorrectly installed piston
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