Yamaha WR250R Service Manual page 29

Valve face width B (intake)
Valve face width B (exhaust)
Valve seat width C (intake)
Valve seat width C (exhaust)
Valve margin thickness D (intake)
Limit
Valve margin thickness D (exhaust)
Limit
Valve stem diameter (intake)
Valve stem diameter (exhaust)
Valve guide inside diameter (intake)
Valve guide inside diameter (exhaust)
Valve-stem-to-valve-guide clearance (intake)
Limit
Valve-stem-to-valve-guide clearance (exhaust)
Limit
Valve stem runout
Cylinder head valve seat width (intake)
Cylinder head valve seat width (exhaust)
Valve spring
Free length (intake)
Limit
Free length (exhaust)
Limit
Installed length (intake)
Installed length (exhaust)
Spring rate K1 (intake)
A
B
C
D
ENGINE SPECIFICATIONS
1.840 mm (0.0724 in)
2.260 mm (0.0890 in)
0.90–1.10 mm (0.0354–0.0433 in)
0.90–1.10 mm (0.0354–0.0433 in)
1.15–1.45 mm (0.0453–0.0571 in)
1.00 mm (0.04 in)
0.85–1.15 mm (0.0335–0.0453 in)
0.70 mm (0.03 in)
4.475–4.490 mm (0.1762–0.1768 in)
4.460–4.475 mm (0.1756–0.1762 in)
4.500–4.512 mm (0.1772–0.1776 in)
4.500–4.512 mm (0.1772–0.1776 in)
0.010–0.037 mm (0.0004–0.0015 in)
0.080 mm (0.0032 in)
0.025–0.052 mm (0.0010–0.0020 in)
0.100 mm (0.0039 in)
0.010 mm (0.0004 in)
0.90–1.10 mm (0.0354–0.0433 in)
0.90–1.10 mm (0.0354–0.0433 in)
36.03 mm (1.42 in)
34.23 mm (1.35 in)
36.03 mm (1.42 in)
34.23 mm (1.35 in)
31.00 mm (1.22 in)
31.00 mm (1.22 in)
31.47 N/mm (179.69 lb/in) (3.21 kgf/mm)
2-4