Yamaha WR426F(N), Owner'S Service Manual

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ENG
CYLINDER AND PISTON
2. Measure:
●
Piston pin-to-piston clearance
ASSEMBLY AND INSTALLATION
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.
Measurement steps:
●
Measure the outside diameter (piston pin)
a
.
If out of specification, replace the piston
pin
Outside diameter (piston pin):
WR426F: 18.991 ~ 19.000 mm
(0.7477 ~ 0.7480 in)
WR400F: 17.991 ~ 18.000 mm
(0.7083 ~ 0.7093 in)
●
Measure the inside diameter (piston)
b
.
Inside diameter (piston):
WR426F: 19.004 ~ 19.015 mm
(0.7482 ~ 0.7486 in)
WR400F: 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)