Crankshaft/Piston/Cylinder; Service Information; Specifications; Troubleshooting - KYMCO VENOX 250 Service Manual

7

. CRANKSHAFT/PISTON/CYLINDER

SERVICE INFORMATION

GENERAL INSTRUCTIONS
• Both of crankcase need to be replaced if anyone crankcase is damaged.
• 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-groove
clearance
Ring end gap
Piston/
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.
Connecting rod big end side clearance
Crankshaft runout
Crank-to-crankcase clearance

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
• Worn, stuck or broken piston rings
• Worn or damaged cylinder or piston
Compression too high
• Excessive carbon build-up in combustion
chamber or on piston head
Top
Second
Top
Second
Oil side rail
15.994～15.997
16.013～16.028
Standard (mm)
VENOX 250
58.0～58.015
⎯
0.1
0.005
0.02～0.06
0.02～0.06
0.1～0.25
0.2～0.35
0.2～0.7
57.975～57.99
10mm from bottom of skirt
0.005～0.065
16.0～16.006
0.001～0.007
⎯
⎯
0.07～0.27
Excessive smoke from exhaust muffler
• Worn or damaged piston rings
• Worn or damaged cylinder or piston
Abnormal noisy piston
• Worn cylinder, piston or piston rings
• Worn piston pin hole or piston pin
VENOX 250
Service Limit (mm)
VENOX 250
58.30
⎯
0.2
0.01
0.09
0.09
0.5
0.5
0.9
57.80
0.125
16.012
15.90
0.01
16.032
0.40
0.10
0.3.
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