Yamaha TT-R90(S), Owner'S Service Manual

Page: 230 / 364

4 - 23
ENG
CYLINDER AND PISTON
Cylinder bore “C”
47.000 ~ 47.005 mm
(1.8504 ~ 1.8506 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
4 mm (0.16 in) from the piston bottom edge.
Piston size P
Standard
46.960 ~ 46.975 mm
(1.8488 ~ 1.8494 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:
0.025 ~ 0.045 mm
(0.0010 ~ 0.0018 in)
<Limit>: 0.15 mm (0.0059 in)
●
If out of specification, replace the cylinder,
and replace the piston and piston rings as
set.