Yamaha 5KM2-AE1, Service Manual

Page: 182 / 431

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ENG
CYLINDER AND PISTON
CHECKING THE PISTON PIN
1.Check:
●
Piston pin
Blue discoloration/grooves
→
Replace, then
inspect the lubrication system.
2.Measure:
●
Piston pin-to-piston clearance
*****************************************************
Measurement steps:
●
Measure the piston pin outside diameter
a
.
If out of specification, replace the piston pin.
●
Measure the piston inside diameter
b
.
●
Calculate the piston pin-to-piston clearance
with the following formula.
●
If out of specification, replace the piston.
*****************************************************
INSTALLING THE PISTON
1.Install:
●
Piston rings
(onto the piston)
NOTE:
●
Be sure to install the piston rings so that the
manufacturer’s marks or numbers are
located on the upper side of the rings.
●
Lubricate the piston and piston rings liberally
with engine oil.
Outside diameter (piston pin):
21.991 ~ 22.000 mm
(0.8658 ~ 0.8661 in)
<Limit>: 21.971 mm (0.8650 in)
Piston pin bore inside diameter:
22.004 ~ 22.015 mm
(0.8663 ~ 0.8667 in)
<Limit>: 22.045 mm (0.8679 in)
Piston pin-to-piston clearance =
Bore size (piston pin)
b
–
Outside diameter (piston pin)
a
Piston pin-to-piston clearance:
0.004 ~ 0.024 mm
(0.00016 ~ 0.00094 in)
<Limit>: 0.07 mm (0.003 in)