Yamaha YXR70FX, Руководство по обслуживанию

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ENG
CYLINDER AND PISTON
2. Measure:
• piston-to-cylinder clearance
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a. Measure the cylinder bore “C” with a cylin-
der bore gauge.
TIP:
_
Measure the cylinder bore “C” in parallel to and
at right angles to the crankshaft. Then, find the
average of the measurements.
b. If out of specification, replace the cylinder,
and the piston and piston rings as a set.
c. Measure piston skirt diameter “P” with the
micrometer.
a
10 mm (0.39 in) from the bottom edge of the pis-
ton
d. If out of specification, replace the piston and
piston rings as a set.
e. Calculate the piston-to-cylinder clearance
with the following formula.
Cylinder bore
“C” 102.000 ~ 102.010 mm
(4.0157 ~ 4.0161 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
)
Piston size “P”
Standard
101.955 ~ 101.970 mm
(4.0140 ~ 4.0146 in)
Piston-to-cylinder clearance =
Cylinder bore “C” –
Piston skirt diameter “P”
Piston-to-cylinder clearance
0.030 ~ 0.055 mm
(0.0012 ~ 0.0022 in)
<Limit>: 0.13 mm (0.051 in)