Yamaha WR450F 2021, Owner'S Service Manual

Page: 56 / 402

ENGINE SPECIFICATIONS
2-3
Valve dimensions
Valve seat contact width limit (intake) 1.5 mm (0.06 in)
Valve seat contact width limit (exhaust) 1.5 mm (0.06 in)
Valve stem diameter limit (intake) 5.445 mm (0.2144 in)
Valve stem diameter limit (exhaust) 5.435 mm (0.2140 in)
Valve guide inside diameter (intake) 5.500–5.512 mm (0.2165–0.2170 in)
Valve guide inside diameter (exhaust) 5.500–5.512 mm (0.2165–0.2170 in)
Valve-stem-to-valve-guide clearance limit
(intake)
0.080 mm (0.0032 in)
Valve-stem-to-valve-guide clearance limit
(exhaust)
0.100 mm (0.0039 in)
Valve stem runout 0.020 mm (0.0008 in)
Valve spring
Free length limit (intake) 36.65 mm (1.44 in)
Free length limit (exhaust) 35.55 mm (1.40 in)
Cylinder
Bore 97.000–97.010 mm (3.8189–3.8193 in)
Wear limit 97.060 mm (3.8213 in)
Piston
Piston-to-cylinder clearance 0.010–0.045 mm (0.0004–0.0018 in)
Diameter 96.955–96.970 mm (3.8171–3.8177 in)
Measuring point (from piston skirt bottom) 9.0 mm (0.35 in)
Piston pin bore inside diameter limit 18.045 mm (0.7104 in)
Piston pin outside diameter limit 17.981 mm (0.7079 in)
Piston-pin-to-piston-pin-bore clearance 0.004–0.024 mm (0.0002–0.0009 in)
Piston ring
Top ring
End gap limit 0.55 mm (0.0217 in)
Ring side clearance 0.015–0.065 mm (0.0006–0.0026 in)
Side clearance limit 0.120 mm (0.0047 in)
2nd ring
End gap limit 0.85 mm (0.0335 in)
Ring side clearance 0.020–0.060 mm (0.0008–0.0024 in)
Side clearance limit 0.100 mm (0.0039 in)
Crankshaft
Crank assembly width 61.93–62.00 mm (2.438–2.441 in)
Runout limit 0.030 mm (0.0012 in)
Clutch
Clutch type Wet, multiple-disc
Clutch lever free play 7.0–12.0 mm (0.28–0.47 in)
Friction plate 1 thickness 2.92–3.08 mm (0.115–0.121 in)
Wear limit 2.82 mm (0.111 in)
Plate quantity 6 pcs
Friction plate 2 thickness 2.92–3.08 mm (0.115–0.121 in)
Wear limit 2.82 mm (0.111 in)
Plate quantity 2 pcs
Clutch plate thickness 1.50–1.70 mm (0.059–0.067 in)
Plate quantity 7 pcs
Warpage limit 0.10 mm (0.004 in)
Clutch spring free length 48.00 mm (1.89 in)