Yamaha F4B, Service Manual

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Power unit technical data
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Crankcase assembly
Item Unit
Model
F4BMH F5AMH F6CMH
Crankcase
Crankshaft journal inside
diameter
mm (in) 25.020–25.041 (0.9850–0.9859)
Camshaft journal inside
diameter
mm (in) 15.000–15.018 (0.5906–0.5913)
Oil pump
Rotor housing inside diame-
ter
mm (in) 23.130–23.160 (0.9106–0.9118)
Outer rotor diameter mm (in) 22.980–23.000 (0.9047–0.9055)
Outer rotor height mm (in) 9.950–9.980 (0.3917–0.3929)
Inner rotor height mm (in) 9.950–9.980 (0.3917–0.3929)
Piston
Diameter mm (in) 61.950–61.965 (2.4390–2.4396)
Measuring point mm (in) 1.0 (0.04)
Oversize diameter
1st mm (in) 62.200–62.215 (2.4488–2.4494)
2nd mm (in) 62.450–62.465 (2.4587–2.4592)
Piston clearance mm (in) 0.035–0.065 (0.0014–0.0026)
Ring groove (Top) mm (in) 1.210–1.230 (0.0476–0.0484)
Ring groove (2nd) mm (in) 1.210–1.230 (0.0476–0.0484)
Ring groove (Oil) mm (in) 2.010–2.030 (0.0791–0.0799)
Pin boss inside diameter mm (in) 15.004–15.015 (0.5907–0.5911)
Pin outside diameter mm (in) 14.995–15.000 (0.5904–0.5906)
Cylinder
Bore mm (in) 62.000–62.015 (2.4409–2.4415)
Piston ring
End gap measuring point
(*1)
mm (in) 60.0 (2.36)
Top ring
Type Barrel
Dimension height (B) mm (in) 1.170–1.190 (0.0461–0.0469)
Dimension width (T) mm (in) 2.500–2.700 (0.0984–0.1063)
End gap (*1) mm (in) 0.110–0.210 (0.0043–0.0083)
Side clearance mm (in) 0.020–0.060 (0.0008–0.0024)
2nd ring
Type Taper
Dimension height (B) mm (in) 1.170–1.190 (0.0461–0.0469)
Dimension width (T) mm (in) 2.600–2.800 (0.1024–0.1102)
End gap (*1) mm (in) 0.260–0.410 (0.0102–0.0161)
Side clearance mm (in) 0.020–0.060 (0.0008–0.0024)
Oil ring
Dimension height (B) mm (in) 1.850–2.000 (0.0728–0.0787)
Dimension width (T) (*1) mm (in) 2.550–2.850 (0.1004–0.1122)
End gap (*1) mm (in) 0.200–0.700 (0.0079–0.0276)
Side clearance mm (in) 0.010–0.180 (0.0004–0.0071)