Yamaha Raptor 90 YFM90RA 2011 Service Manual page 120

CYLINDER AND PISTON
Cylinder bore "C"
Taper limit "T"
Out-of-round "R"
"C" = maximum of D
"T" = maximum of D
maximum of D
"R" = maximum of D
minimum of D
b. If out of specification, rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
c. Measure piston skirt diameter "P" with the
micrometer.
a 5 mm (0.20 in) from the bottom edge of the pis-
ton
Standard
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.
Piston-to-cylinder clearance =
Cylinder bore "C" –
Piston skirt diameter "P"
Piston-to-cylinder clearance
0.010 ~ 0.040 mm
(0.0004 ~ 0.0016 in)
<Limit>: 0.10 mm (0.0039 in)
f. If out of specification, rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
4 - 23
ENG
47.00 ~ 47.01 mm
(1.8504 ~ 1.8508 in)
0.05 mm (0.002 in)
0.01 mm (0.0004 in)
~ D
1 2
or D –
1 2
or D
5 6
, D or D –
1 3 5
, D or D
2 4 6
Piston size "P"
46.97 ~ 46.99 mm
(1.8492 ~ 1.8500 in)