Yamaha WR250F(S), Owner'S Service Manual, Page: 85 / 864

MAINTENANCE SPECIFICATIONS
2 - 6
SPEC
Stem runout limit ---- 0.01 mm
(0.0004 in)
Valve seat width IN 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in) 1.6 mm
(0.0630 in)
EX 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in) 1.6 mm
(0.0630 in)
Valve spring:
Free length IN 37.81 mm (1.49 in) 36.81 mm
(1.45 in)
EX 37.54 mm (1.48 in) 36.54 mm
(1.44 in)
Set length (valve closed) IN 29.13 mm (1.15 in) ----
EX 29.30 mm (1.15 in) ----
Compressed force (installed) IN 99 ~ 114 N at 29.13 mm
(9.9 ~ 11.4 kg at 29.13 mm,
22.27 ~ 25.57 lb at 1.15 in) ----
EX 126 ~ 144 N at 29.30 mm
(12.6 ~ 14.4 kg at 29.30 mm,
28.44 ~ 32.41 lb at 1.15 in) ----
Tilt limit IN ---- 2.5°/ 1.7 mm
(2.5°/0.067 in)
EX ---- 2.5°/1.6 mm
(2.5°/0.063 in)
Direction of winding (top view) IN Clockwise ----
EX Clockwise ----
Piston:
Piston to cylinder clearance 0.040 ~ 0.065 mm
(0.0016 ~ 0.0026 in) 0.1 mm
(0.004 in)
Piston size “D” 76.955 ~ 76.970 mm
(3.0297 ~ 3.0303 in) ----
Measuring point “H” 8 mm (0.31 in) ----
Piston off-set 0.5 mm (0.020 in)/IN-side ----
Item Standard Limit
*
H
D