ENG
CYLINDER AND PISTON
2. Measure:
• piston-to-cylinder clearance
TTTTTTTTTTTTTTTTTTTTTTTTTTTT
T
T
TTTTTT
T
T
T
T
a. Measure the cylinder diameter “C” with the
cylinder bore gauge.
b. If out of specification, replace the cylinder, the
piston and piston rings as a set.
c. Measure piston skirt diameter “P” with the
micrometer.
a
5 mm from the bottom edge of the piston
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.
f.
If out of specification, replace the cylinder, the
piston and piston rings as a set.
Piston-to-cylinder clearance = (Cylinder bore
“C”) - (piston skirt diameter “P”)
T TT
T TT
T TT
T TT
T TT
T TT
T TT
T TT
T TT
T
T
T
T TT
T TT
T
T
T
T
Measure cylinder bore “C” by taking side-to-side
and front-to-back measurements of the cylinder.
Then, find the average of the measurements.
NOTE:
P
a
5-32
Cylinder bore “C”
74.000 ~74.016mm
(2.913 ~2.194 in)
Wear limit
74.10mm
(2.917 in)
Taper limit “T”
0.050mm
(0.0020 in)
Out of round “R”
0.005mm
(0.0002 in)
“C” = maximum of D
1
~ D
2
“T” = maximum of D
1
or D
2
- maximum of D
5
or D
6
“R” = maximum of D
1
, D
3
or D
5
- (minimum of
D
2
, D
4
or D
6
)
Piston size diameter
73.983 ~ 73.998 mm
(2.9127 ~2.9133 in)
Piston-to-cylinder clearance
0.010 ~ 0.025mm
(0.0004 ~ 0.0010 in)
<limit>: 0.15 mm (0.006 in)
Summary of Contents for YBR250 2007
Page 1: ...YBR250 SERVICE MANUAL 5D1 F8197 E0 2007 ...
Page 2: ......
Page 359: ...YAMAHA MOTOR DA AMAZÔNIA LTDA ...
