Yamaha YZ250(W)/W1 Owner's Service Manual page 266

CYLINDER HEAD, CYLINDER AND PISTON
5. Check:
9 Free play
There should be no noticeable free play.
Free play exists ¡ Inspect the connecting
rod for wear/Replace the pin and/or con-
necting rod as required.
EC474502
Piston ring
1. Install:
9 Piston ring
Into the cylinder.
Push the ring with the piston crown.
2. Measure:
9 End gap
Use a thickness gauge 1.
Out of limit ¡ Replace.
Ring end gap (installed):
Standard
0.40~0.55 mm
(0.016~0.022 in)
3. Measure:
9 Side clearance
Use a thickness gauge 1.
Out of limit ¡ Replace piston and/or ring.
Side clearance:
Standard
0.030~0.065 mm
(0.0012~0.0026 in)
NOTE:
Check at several points.
4-24
ENG
<Limit>
0.95 mm
(0.037 in)
<Limit>
0.1 mm
(0.004 in)