Yamaha YZ450FF 1SL-28199-11, Owner'S Service Manual

Page: 43 / 358

ENGINE SPECIFICATIONS
2-4
Valve seat width C (intake) 0.90–1.10 mm (0.0354–0.0433 in)
Valve seat width C (exhaust) 0.90–1.10 mm (0.0354–0.0433 in)
Valve margin thickness D (intake) 1.20 mm (0.0472 in)
Valve margin thickness D (exhaust) 0.85 mm (0.0335 in)
Valve stem diameter (intake) 5.475–5.490 mm (0.2156–0.2161 in)
Limit 5.445 mm (0.2144 in)
Valve stem diameter (exhaust) 5.465–5.480 mm (0.2152–0.2157 in)
Limit 5.435 mm (0.2140 in)
Valve guide inside diameter (intake) 5.500–5.512 mm (0.2165–0.2170 in)
Limit 5.550 mm (0.2185 in)
Valve guide inside diameter (exhaust) 5.500–5.512 mm (0.2165–0.2170 in)
Limit 5.550 mm (0.2185 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) 0.020–0.047 mm (0.0008–0.0019 in)
Limit 0.100 mm (0.0039 in)
Valve stem runout 0.010 mm (0.0004 in)
Valve spring
Free length (intake) 40.76 mm (1.60 in)
Limit 39.76 mm (1.57 in)
Free length (exhaust) 37.01 mm (1.46 in)
Limit 36.01 mm (1.42 in)
Installed length (intake) 34.78 mm (1.37 in)
Installed length (exhaust) 30.83 mm (1.21 in)
Spring rate K1 (intake) 31.90 N/mm (3.25 kgf/mm, 182.15 lbf/in)
Spring rate K2 (intake) 41.37 N/mm (4.22 kgf/mm, 236.22 lbf/in)
Spring rate K1 (exhaust) 21.46 N/mm (2.19 kgf/mm, 122.54 lbf/in)
Spring rate K2 (exhaust) 27.84 N/mm (2.84 kgf/mm, 158.97 lbf/in)
Installed compression spring force (intake) 178.00–204.00 N (18.15–20.80 kgf,
40.01–45.86 lbf)
Installed compression spring force (exhaust) 124.00–142.00 N (12.64–14.48 kgf,
27.88–31.92 lbf)
C
D