Yamaha XT250X 2008, Service Manual, Page: 23 / 282

ENGINE SPECIFICATIONS
2-4
Valve margin thickness D (intake) 0.80–1.20 mm (0.0315–0.0472 in)
Valve margin thickness D (exhaust) 0.80–1.20 mm (0.0315–0.0472 in)
Valve stem diameter (intake) 5.975–5.990 mm (0.2352–0.2358 in)
Limit 5.950 mm (0.2343 in)
Valve stem diameter (exhaust) 5.960–5.975 mm (0.2346–0.2352 in)
Limit 5.935 mm (0.2337 in)
Valve guide inside diameter (intake) 6.000–6.012 mm (0.2362–0.2367 in)
Limit 6.042 mm (0.2379 in)
Valve guide inside diameter (exhaust) 6.000–6.012 mm (0.2362–0.2367 in)
Limit 6.042 mm (0.2379 in)
Valve-stem-to-valve-guide clearance (intake) 0.010–0.037 mm (0.0004–0.0015 in)
Limit 0.080 mm (0.0032 in)
Valve-stem-to-valve-guide clearance (exhaust) 0.025–0.052 mm (0.0010–0.0020 in)
Limit 0.100 mm (0.0039 in)
Valve stem runout 0.030 mm (0.0012 in)
Cylinder head valve seat width (intake) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.7 mm (0.07 in)
Cylinder head valve seat width (exhaust) 0.90–1.10 mm (0.0354–0.0433 in)
Limit 1.7 mm (0.07 in)
Valve spring
Inner spring
Free length (intake) 36.17 mm (1.42 in)
Limit 34.47 mm (1.36 in)
Free length (exhaust) 36.17 mm (1.42 in)
Limit 34.47 mm (1.36 in)
Installed length (intake) 30.50 mm (1.20 in)
Installed length (exhaust) 30.50 mm (1.20 in)
Spring rate K1 (intake) 14.70 N/mm (83.94 lb/in) (1.50 kgf/mm)
Spring rate K2 (intake) 19.00 N/mm (108.49 lb/in) (1.94 kgf/mm)
Spring rate K1 (exhaust) 14.70 N/mm (83.94 lb/in) (1.50 kgf/mm)
Spring rate K2 (exhaust) 19.00 N/mm (108.49 lb/in) (1.94 kgf/mm)
Installed compression spring force (intake) 75.00–91.70 N (16.86–20.61 lbf) (7.65–9.35 kgf)
Installed compression spring force (exhaust) 75.00–91.70 N (16.86–20.61 lbf) (7.65–9.35 kgf)
Spring tilt (intake) 2.5
°
/1.6 mm
Spring tilt (exhaust) 2.5
°
/1.6 mm
C
D
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