SANYANG INDUSTRY CO. SYM, Service Manual

Page: 77 / 176

7.CYLINDER/PISTON PEUGEOT
7-2
PRECAUTIONS IN OPERATION
General Information
y
Both cylinder and piston service cannot be carried out when engine mounted on frame.
Specification unit: mm
Item Standard Limit
ID 37.00 -
Bend/wrap age
－
0.050
Roundness 0.005 0.050
Cylinder
Cylindrical 0.005 0.050
Top ring 0.025~0.060 0.090
Clearance between
piston and rings
2
nd
ring 0.015~0.050 0.090
Top ring 0.200~0.400 0.500
2
nd
ring 0.250~0.400 0.650 Ring-end gap
Oil ring
0.200~0.700 -
OD of piston 37.005~36.985 -
Clearance between piston and
cylinder
0.025~0.040 0.100
Piston/
Piston ring
ID of piston pin hole 13.002~13.008 13.040
OD of piston pin 12.994~13.000 12.980
Clearance between piston and piston pin 0.002~0.014 0.018
ID of connecting rod small-end 13.005~13.020 13.040
TROUBLE DIAGNOSIS
Low Or Unstable Compression Pressure
z
Cylinder or piston ring worn out.
z
Compress pressure to high.
z
Too much carbon deposited in
combustion chamber and piston.
Knock or Noise
z
Cylinder or piston ring worn out.
z
Carbon deposits on cylinder head
top-side.
z
Piston pin hole and piston pin wear out.
Smoking in Exhaust Pipe
z
Piston or piston ring worn out.
z
Piston ring installation improperly.
z
Cylinder or piston damage.
Engine Overheat
z
Carbon deposits on cylinder head top
side.