Yamaha WR450F Owner's Service Manual page 55

Valve spring
Free length (intake)
Limit
Free length (exhaust)
Limit
Installed length (intake)
Installed length (exhaust)
Spring rate K1 (intake)
Spring rate K2 (intake)
Spring rate K1 (exhaust)
Spring rate K2 (exhaust)
Installed compression spring force (intake)
Installed compression spring force (exhaust)
Spring tilt (intake)
Spring tilt (exhaust)
Winding direction (intake)
Winding direction (exhaust)
Cylinder
Bore
Taper limit
Out of round limit
Piston
Piston-to-cylinder clearance
Limit
Diameter
Measuring point (from piston skirt bottom)
Offset
Piston pin bore inside diameter
Limit
Piston pin outside diameter
Limit
Piston ring
Top ring
Ring type
Dimensions (B  T)
End gap (installed)
Limit
Ring side clearance
Limit
2nd ring
Ring type
Dimensions (B  T)
End gap (installed)
Limit
Ring side clearance
Limit
Oil ring
Dimensions (B  T)
End gap (installed)
ENGINE SPECIFICATIONS
40.76 mm (1.60 in)
38.72 mm (1.52 in)
36.94 mm (1.45 in)
35.09 mm (1.38 in)
34.78 mm (1.37 in)
30.83 mm (1.21 in)
31.90 N/mm (3.25 kgf/mm, 182.15 lbf/in)
41.37 N/mm (4.22 kgf/mm, 236.22 lbf/in)
21.76 N/mm (2.22 kgf/mm, 124.25 lbf/in)
28.12 N/mm (2.87 kgf/mm, 160.57 lbf/in)
178.00–204.00 N (18.15–20.80 kgf,
40.01–45.86 lbf)
124.00–142.00 N (12.64–14.48 kgf,
27.88–31.92 lbf)
2.5 °/1.8 mm (2.5 °/0.07 in)
2.5 °/1.6 mm (2.5 °/0.06 in)
Clockwise
Clockwise
97.000–97.010 mm (3.8189–3.8193 in)
0.050 mm (0.0020 in)
0.050 mm (0.0020 in)
0.030–0.055 mm (0.0012–0.0022 in)
0.15 mm (0.006 in)
96.955–96.970 mm (3.8171–3.8177 in)
9.0 mm (0.35 in)
0.00 mm (0.0000 in)
18.004–18.015 mm (0.7088–0.7093 in)
18.045 mm (0.7104 in)
17.991–18.000 mm (0.7083–0.7087 in)
17.971 mm (0.7075 in)
Barrel
1.00  3.30 mm (0.04  0.13 in)
0.20–0.30 mm (0.0079–0.0118 in)
0.55 mm (0.0217 in)
0.015–0.065 mm (0.0006–0.0026 in)
0.120 mm (0.0047 in)
Taper
1.00  3.10 mm (0.04  0.12 in)
0.35–0.50 mm (0.0138–0.0197 in)
0.85 mm (0.0335 in)
0.020–0.060 mm (0.0008–0.0024 in)
0.120 mm (0.0047 in)
1.50  2.25 mm (0.06  0.89 in)
0.20–0.50 mm (0.0079–0.0197 in)
2-4