Precautions In Operation; Trouble Diagnosis - Sym GTS 250 Service Manual

7. Cylinder / Piston

Precautions in Operation

General Information
Both cylinder and piston service cannot be carried out when engine mounted on frame.
UA25A
Specification
ID
Cylinder
Bend
Clearance between piston
rings
Ring-end gap
Piston/
Piston ring
OD of piston (2
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
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
Item
Top ring
nd
2 ring
Top ring
nd
2 ring
Oil ring side rail
nd
)
Standard
70.995~71.015
-
0.015~0.050
0.015~0.050
0.150~0.300
0.300~0.450
0.200~0.700
70.430~70.480
0.010~0.040
17.002~17.008
16.994~17.000
0.002~0.014
17.016~17.034
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
Cooling pipe clogged or not enough in coolant
flow
Unit¡ G mm
Limit
71.100
0.050
0.090
0.090
0.500
0.650
-
70.380
0.100
17.020
16.960
0.020
17.064