Service Information; Troubleshooting - KYMCO GRAND DINK 125 Service Manual

7
. CYLINDER/PISTON

SERVICE INFORMATION

GENERAL INSTRUCTIONS
• The cylinder and piston can be serviced with the engine installed in the frame.
• When installing the cylinder, use a new cylinder gasket and make sure that the dowel pins are
correctly installed.
• After disassembly, clean the removed parts and dry them with compressed air before inspection.
SPECIFICATIONS
I.D.
Warpage
Cylinder
Cylindricity
True roundness
Ring-to-groove
clearance
Piston, Ring end gap
piston ring
Piston O.D.
Piston O.D. measuring position
. Piston-to-cylinder clearance
Piston pin hole I.D.
Piston pin O.D
Piston-to-piston pin clearance
Connecting rod small end I.D. bore

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
• Worn or damaged cylinder and piston rings
• Worn, stuck or broken piston rings
Compression too high
• Excessive carbon build-up in combustion
chamber or on piston head
Item
top
Second
top
Second
Oil side rail
Standard (mm)
SH30DA SH25DA
57.405 57. 52.400
0.01 0.01
415 410
0.01 0.01
0.01 0.01
0.015 0.05 0.015
0 0
0.015 0.05 0.015
0 0
0.15 0.30 0.15
0.15 0.30 0.15
0.2 0.9 0.2
57.375 57. 52.370
9mm from 9mm from
395 390
bottom of skirt bottom of skirt
0.010 0.04 0.010
0 0
15.002 15. 15.002
008 008
14.994 15. 14.994
000 000
0.002 0.01 0.002
4 4
15.016 15. 15.016
034 034
Excessive smoke from exhaust muffler
• Worn or damaged piston rings
• Worn or damaged cylinder and piston
Abnormal noisy piston
• Worn cylinder, piston and piston rings
• Worn piston pin hole and piston pin
• Incorrectly installed piston
GRAND DINK 125/150
Service Limit (mm)
SH30DA SH25DA
52. 57.50 52.50
0.05 0.05
0.05 0.05
0.05 0.05
0.05 0.09 0.09
0.05 0.09 0.09
0.30 0.50 0.50
0.30 0.50 0.50
0.9 æ æ
52. 57.30 52.30
9mm from 9mm from
bottom of bottom of skirt
skirt
0.04 0.01 0.01
15. 15.04 15.04
15. 14.96 14.96
0.01 0.02 0.02
15. 15.06 15.06
7-2