Sym PA12B User Manual

8. Cylinder / Piston
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Precautions in Operation
General Information
z The engine must be removed from the frame before the repairing of the cylinder and the
piston.
Specification Measurement unit：mm
Specification
Subject
Standard Service Limit
Cylinder Inside Diameter 56.000~56.010 56.100
Warpage
－
0.050
Taper
－
0.050
Cylinder
Out of round
－
0.050
Top Ring 0.025~0.055 0.130
Piston Ring/
Groove Clearance
Second Ring 0.015~0.045 0.120
Top Ring 0.150~0.350 0.500
Second Ring 0.150~0.350 0.500
Piston Ring End
Gap
Oil Ring 0.200~0.500
－
Top Ring 1.475~1.490 1.460
Piston Ring
Thickness
Second Ring 1.475~1.490 1.460
Piston Outside Diameter 55.970~55.990 55.8700
Piston Outside Diameter
Measure Point
10mm up from the bottom of the piston
Piston/ Cylinder Clearance 0.020~0.050 0.110
Piston/
Piston Ring
Piston Pin Hole Inside Diameter 15.002~15.008 15.050
Piston Pin Outside Diameter 14.994~15.000 14.850
Piston/ Piston Pin Clearance 0.002~0.014 0.020
Connecting Rod Small End Inside Diameter 15.010~15.028 15.070
Troubleshooting
Low Compression or Instability Excessive Smoke
Worn cylinder or piston or piston rings
Worn cylinder or piston rings
Improper piston rings installation
Over High Compression
Overheating
Excessive carbon built-up on the piston or
combustion chamber
Excessive carbon built-up on the top of the
piston
Knocking or Abnormal Noise
Worn piston or cylinder
Excessive carbon built-up on the top of the
piston
Worn Piston Pin and Piston Pin Hole
8-2

Sym PA12B Specifications

General

Brand	Sym
Model	PA12B
Category	Motorcycle
Language	English