Piston Pin And Small End Bearing Inspection - Yamaha YZ250(R)/LC Owner's Service Manual

CYLINDER HEAD, CYLINDER AND PISTON
3. Measure:
9 Piston skirt diameter
Use micrometer 1.
Measure the specific distance b from the
stepped surface a on inside of the piston.
Out of specification ¡ Replace.
Distance b b
17.5 mm
(0.69 in)
EC474402
Piston pin and small end bearing
1. Inspect:
9 Piston pin
9 Small end bearing
Signs of heat discoloration ¡ Replace.
2. Measure:
9 Piston pin outside diameter
Use micrometer 1.
Out of limit ¡ Replace.
Piston pin outside diameter:
Standard
17.995~18.000 mm
(0.7085~0.7087 in)
3. Check:
9 Free play (when the piston pin 1 is in
place in the piston 2)
There should be no noticeable for the play.
Free play exists ¡ Replace piston pin
and/or piston.
4. Install:
9 Small end bearing
9 Piston pin
Into the small end of connecting rod.
4-23
ENG
Piston dia.
66.352~66.367 mm
(2.6120~2.6129 in)
<Limit>
17.975 mm
(0.7077 in)