Shibaura ST318, Workshop Manual

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42
6) Connecting rod metal
Inspection
(1) Check the metal and if peeling, melting, uneven wear,
improper contact or other damage is noticed, replace
the metal.
(2) Measure the oil clearance of the crank pin and metal
using plasti-gauge.
➀
Remove oil dust or other foreign matter sticked to
the metal and crank pin.
➁ Cut plasti-gauge to the length same as the metal
width and place it on the crank pin in parallel with
the crankshaft avoiding the oil hole.
➂ Install the connecting rod metal and connecting rod
cap and tighten with the specified tightening torque.
Tightening torque
29 – 34 N
·
m
(3.0 – 3.5 kgf · m)
NOTE: Never turn the connecting rod at this time.
➃ Remove the connecting rod cap and measure the
plasti-gauge width with the scale printed on the
gauge envelope.
NOTE: Measure the widest part of the
plasti-gauge.
(3) If the oil clearance exceeds the service limit according
to the result of the measurement, replace the metal or
grind the crank pin and replace with a metal of
undersize.
NOTE:
1. When the crank shaft pin outside is ground,
check the oil clearance before installing it.
2. Grind the crank pin precisely referring to the
paragraph of the crank shaft about the finishing
accuracy and oil holes.
Reassembly (piston and connecting rod)
(1) Heat the piston to about 100°C with a piston heater or
the like and install it aligning the SHIBAURA mark in
the piston and match mark at (A) of the connecting rod.
(2) Care should be taken to the figure match mark at (A) of
the connecting rod.
(3) Install the piston ring to the piston facing the stamp at
the end surface of the ring end gap upward.
(4) When the connecting rod or piston and piston pin are
replaced, weight variation among cylinders with the
rod, piston and piston ring installed should be within
10 g.
Clearance between crank pin and connecting rod metal
(oil clearance) (mm)
Standard assembling value Service limit
0.035 – 0.083 More than 0.2
T126
T127
Metal size Metal code No.
Crankshaft pin
outside dia. Finishing
dimension (
∅
)
S.T.D. 198517130 38.964 – 38.975
U.S. 0.25 198517134 38.714 – 38.725
U.S. 0.50
198517137 38.464 – 38.475
T128