Limits For Service; Troubleshooting - um UXPW125 Service Manual

5.2 Limits for service

Cylinder and Piston
Inner diameter of cylinder
Cylindricity
Cylinder
Flatness
Outer diameter of piston
Inner diameter of piston pin hole
Closure clearance of
piston ring
Piston, Piston
Ring and
gap between piston
Piston Pin
rings and piston rings
Piston/Cylinder Clearance
Outer diameter of piston pin
Clearance between piston pin and piston
pin hole
Small End of Inner diameter
Connecting
Clearance
Rod
connecting rod and piston pin
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.
UXPW 125 ENGINE SERVICE MANUAL AND EFI DIAGNOSTIC
Item
of cylinder face
Top
Second
Oil ring
Top
Second
between small
Standard value
Φ52.400～φ52.410
0.004
0.03
Φ52.38～φ52.39
φ14.002～φ14.008
0.1～0.25
0.15-0.30
0.2～0.7
0.02～0.06
0.02～0.06
0.01～0.03
φ13.994～φ14
0.002～0.014
φ14.015～φ14.028
end of
0.015～0.03
unit：mm
Service Limit
Φ52.5
0.10
0.10
Φ52.3
φ14.04
0.35
0.4
0.85
0.10
0.10
0.07
φ13.96
0.04
φ14.06
0.10
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