Shibaura ST330, Workshop Manual

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35
4) Piston and piston ring
Disassembly
(1) Remove the piston ring using a piston ring tool.
(2) Remove the snap ring and extract the piston pin.
Inspection
(1) Piston
➀
Check the piston for crack, streak and burnout on the
outside surface and replace if remarkable.
➁
Measure the longer diameter at 10 mm above the
lower end of the piston skirt and bore of the cylinder
in the thrust direction, calculate the clearance, and
replace if the repair value is exceeded.
③
Measure the piston pin hole diameter and piston pin
outside diameter and replace if the clearance exceeds
the service limit.
120Y
121Y
122Y
Clearance between cylinder and piston (mm)
Model
Standard
assembling value
Service limit
N843 0.0375 – 0.0715 0.25
Piston skirt bottom longer dia. (mm)
Model
Standard
assembling value
Service limit
N843 ∅ 83.948 － 83.96 ∅ 83.7
Clearance between piston pin hole and piston pin (mm)
Model
Standard
assembling value
Service limit
N843 -0.001
～
+0.007 0.02