Operational Precautions; Trouble Diagnosis - Sym Mio 50 Service Manual

7. Cylinder / Piston

Operational Precautions

General Information
Both cylinder and piston service cannot be carried out when engine mounted on frame.
Specification
Model
Item
ID
Bend / wrap age
Cylinder
Cylindrical roundness
Cylindrical roundness
Clearance
between piston
rings
Ring-end gap
Piston/
Piston ring
OD of piston
Piston OD measurement
position
Clearance between piston
and cylinder
ID of piston pin boss
OD of piston pin
Clearance between piston and piston pin
ID of connecting rod small-end

Trouble Diagnosis

Low or Unstable Compression Pressure
Cylinder or piston ring worn out
High compression Pressure
Carbon deposit onto piston and combustion
chamber
Knock or Noise
Cylinder or piston ring worn out
Carbon deposits on cylinder head top-side
Piston pin hole and piston pin wear out
7-2
To this chapter contents
HU10U/W
Standard
49.995~50.015
¡ Ð
¡ Ð
¡ Ð
top ring 0.015~0.050
nd
2 ring 0.015~0.050
top ring 0.100~0.250
nd
2 ring 0.100~0.250
oil ring 0.300~0.900
49.970~49.990
Lower-end up 9mm
of piston skirt
0.005~0.015
13.002~13.008
12.994~13.000
0.002~0.014
13.016~13.034
Smoking in Exhaust Pipe
Piston or piston ring worn out
Piston ring installation improperly
Cylinder or piston damage
Engine Overheat
Carbon deposits on cylinder head top side
HU05U
Limit Standard
50.500 37.015~36.995
0.050 ¡ Ð
¡ Ð
0.050
¡ Ð
0.050
0.090 0.015~0.050
0.090 0.015~0.050
0.500 0.100~0.250
0.500 0.100~0.250
¡ Ð
0.2~0.7
49.900 36.985~37.005
Lower-end up 9mm
¡ Ð
of piston skirt
0.100 0.005~0.015
13.040 10.002~10.008
12.960 10.000~10.006
0.020 0.002~0.014
13.060 10.016~10.034
Unit: mm
Limit
37.500
0.050
0.050
0.050
0.090
0.090
0.500
0.500
¡ Ð
36.900
¡ Ð
0.100
10.040
9.966
0.020
10.060