Yamaha WR450F, Owner'S Service Manual

Page: 416 / 794

4 - 48
ENG
CYLINDER AND PISTON
Cylinder bore “C”
95.00 ~ 95.01 mm
(3.7402 ~ 3.7406 in)
Taper limit “T” 0.05 mm (0.002 in)
Out of round “R” 0.05 mm (0.002 in)
“C” = Maximum D
“T” = (Maximum D
1
or D
2
)
– (Maximum D
5
or D
6
)
“R” = (Maximum D
1
, D
3
or D
5
)
– (Minimum D
2
, D
4
or D
6
)
• If out of specification, replace the cylinder,
and replace the piston and piston rings as
set.
2nd step:
• Measure the piston skirt diameter “P” with
a micrometer.
a
8 mm (0.315 in) from the piston bottom edge
Piston size “P”
Standard
94.945 ~ 94.960 mm
(3.738 ~ 3.739 in)
• If out of specification, replace the piston
and piston rings as a set.
3rd step:
• Calculate the piston-to-cylinder clearance
with following formula:
Piston-to-cylinder clearance =
Cylinder bore “C” –
Piston skirt diameter “P”
Piston-to-cylinder clearance:
0.040 ~ 0.065 mm
(0.0016 ~ 0.0026 in)
<Limit>: 0.1 mm (0.004 in)
• If out of specification, replace the cylinder,
and replace the piston and piston rings as
set.