UXPW
125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
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44
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5.2
Limits for service
Cylinder and Piston
unit
:
mm
Item
Standard value
Service Limit
Cylinder
Inner diameter of cylinder
Φ52.400
~
φ52.410
Φ52.5
Cylindricity
0.004
0.10
Flatness
of cylinder face
0.03
0.10
Piston, Piston
Ring and
Piston Pin
Outer diameter of piston
Φ52.38
~
φ52.39
Φ52.3
Inner diameter of piston pin hole
φ14.002
~
φ14.008
φ14.04
Closure clearance of
piston ring
Top
0.1
~
0.25
0.35
Second
0.15
-
0.30
0.4
Oil ring
0.2
~
0.7
0.85
gap between piston
rings and piston rings
Top
0.02
~
0.06
0.10
Second
0.02
~
0.06
0.10
Piston/Cylinder Clearance
0.01
~
0.03
0.07
Outer diameter of piston pin
φ13.994
~
φ14
φ13.96
Clearance between piston pin and piston
pin hole
0.002
~
0.014
0.04
Small End of
Connecting
Rod
Inner diameter
φ14.015
~
φ14.028
φ14.06
Clearance between small end of
connecting rod and piston pin
0.015
~
0.03
0.10
Tightening torque of AB bolt: 11N.m
5.3
Troubleshooting
5.3.1. Cylinder pressure is too low or there is no cylinder pressure (performance at low speed is
not acceptable)
•
Severely worn or broken piston ring
•
Damaged or broken cylinder block or piston
5.3.2. Cylinder pressure is too high. Engine overheats.
•
Too much carbon deposit on piston top
5.3.3. Engine oil is consumed significantly, and engine smokes heavily.
•
Severely worn or broken cylinder block and piston
•
Improper assembly of piston ring
5.3.4. Abnormal noise
•
Improper assembly of piston
•
Fit clearance is too large between piston and piston pin, and the cylinder block and
piston are severely worn.
Summary of Contents for UXPW125
Page 1: ...UXPW125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC...
Page 16: ...UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC 16 3 1 Lubrication system schematic diagram...
Page 24: ...UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC 24 4 1 Cylinder Head exploded view...
Page 37: ...UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC 37...
Page 43: ...UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC 43 5 1 Cylinder block piston exploded view...
Page 85: ...UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC 85 8 1 Crankcase exploded view...