KYMCO SUPER8 50 Service Manual page 88

8
. CYLINDER/PISTON
SERVICE INFORMATION.......................8-1
TROUBLESHOOTING..............................8-1
CYLINDER REMOVAL ...........................8-2
SERVICE INFORMATION
GENERAL INSTRUCTIONS
• The cylinder and piston can be serviced with the engine installed in the frame.
• After disassembly, clean the removed parts and dry them with compressed air before inspection.
SPECIFICATIONS
Item
I.D.
Warpage
Cylinder
Cylindricity
True roundness
Ring-to-
clearance
Ring end gap
Piston,
piston ring
Piston O.D.
Piston O.D. measuring
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, stuck or broken piston rings
• Worn or damaged cylinder and piston
Compression too high
• Excessive carbon build-up in combustion
chamber or on piston head
8-1
PISTON REMOVAL................................. 8-2
PISTON INSTALLATION........................ 8-6
CYLINDER INSTALLATION ................. 8-6
Standard (mm)
50.00-50.01
Top 0.015-0.050
Second 0.015-0.050
Top
Second
Oil side rail
49.97-49.990
9mm from bottom of skirt
0.010-0.040
13.002-13.008
12.994-13.000
0.002-0.014
13.016-13.034
Service Limit (mm)
⎯
⎯
⎯
0.08-0.20
0.05-0.20
0.20-0.70
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
SUPER8 50
0.05
0.05
0.05
0.09
0.09
0.45
0.45
⎯
49.9
⎯
0.1
13.04
12.96
⎯
13.06