Yamaha YZ450FT Automobile User Manual


 
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ENG
CYLINDER AND PISTON
Piston pin
1. Inspect:
Piston pin
Blue discoloration/grooves Replace,
then inspect the lubrication system.
2. Measure:
Piston pin-to-piston clearance
ASSEMBLY AND INSTALLATION
Piston
1. Install:
Piston rings
Onto the piston.
N
OTE:
Be sure to install the piston rings so that the
manufacturers marks or numbers are
located on the upper side of the rings.
Lubricate the piston and piston rings liberally
with engine oil.
Measurement steps:
Measure the outside diameter (piston pin)
a.
If out of specification, replace the piston
pin.
Outside diameter (piston pin):
17.991 ~ 18.000 mm
(0.7083 ~ 0.7087 in)
Measure the inside diameter (piston) b.
Inside diameter (piston):
18.004 ~ 18.015 mm
(0.7088 ~ 0.7093 in)
Calculate the piston pin-to-piston clear-
ance with the following formula.
Piston pin-to-piston clearance =
Inside diameter (piston)
b
Outside diameter (piston pin)
a
If out of specification, replace the piston.
Piston pin-to-piston clearance:
0.004 ~ 0.024 mm
(0.00016 ~ 0.00094 in)
<Limit>: 0.07 mm (0.003 in)