Yamaha F80A, Service Manual, Page: 22 / 79

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SPEC
E
MAINTENANCE SPECIFICATIONS
Stem diameter
Intake mm (in) 5.975 ~ 5.990 (0.2352 ~ 0.2358)
Exhaust mm (in) 5.960 ~ 5.975 (0.2346 ~ 0.2352)
Guide inside diameter
Intake and exhaust mm (in) 6.005 ~ 6.018 (0.2364 ~ 0.2369)
Stem-to-guide clearance
Intake mm (in) 0.015 ~ 0.043 (0.0006 ~ 0.0017)
Exhaust mm (in) 0.030 ~ 0.058 (0.0012 ~ 0.0023)
Stem runout limit mm (in) 0.03 (0.001)
VALVE SPRINGS
Free length mm (in) 53.20 (2.094)
Minimum free length mm (in) 52.25 (2.057)
Tilt limit mm (in) 2.6 (0.10)
VALVE LIFTERS
Valve lifter outside diameter mm (in) 27.965 ~ 27.980 (1.1010 ~ 1.1016)
Valve-lifter-to-cylinder-head
clearance mm (in) 0.020 ~ 0.056 (0.0008 ~ 0.0022)
VALVE PADS
Valve pad thickness
(in 0.025 mm increments) mm (in) 2.000 ~ 3.300 (0.0787 ~ 0.1299)
PISTONS
Piston-to-cylinder clearance mm (in) 0.070 ~ 0.080 (0.0028 ~ 0.0031)
Measuring point (D) mm (in) 78.928 ~ 78.949 (3.1074 ~ 3.1082)
Measuring point (H) mm (in) 13 (0.51)
Pin boss inside
diameter mm (in) 18.008 ~ 18.015 (0.7090 ~ 0.7093)
Oversize piston diameter mm (in) 79.25 (3.120)
PISTON PINS
Outside diameter mm (in) 17.997 ~ 18.000 (0.7085 ~ 0.7087)
PISTON RINGS
Top ring
Dimension B mm (in) 1.17 ~ 1.19 (0.046 ~ 0.047)
Dimension T mm (in) 2.89 ~ 2.91 (0.114 ~ 0.115)
End gap mm (in) 0.15 ~ 0.30 (0.006 ~ 0.012)
Side clearance mm (in) 0.02 ~ 0.08 (0.001 ~ 0.003)
2nd ring
Dimension B mm (in) 1.47 ~ 1.49 (0.058 ~ 0.059)
Dimension T mm (in) 3.00 ~ 3.20 (0.118 ~ 0.126)
End gap mm (in) 0.70 ~ 0.90 (0.028 ~ 0.035)
Side clearance mm (in) 0.03 ~ 0.07 (0.001 ~ 0.003)
Oil ring
Dimension B mm (in) 2.38 ~ 2.48 (0.094 ~ 0.098)
Dimension T mm (in) 2.40 (0.094)
End gap mm (in) 0.20 ~ 0.70 (0.008 ~ 0.028)
Side clearance mm (in) 0.03 ~ 0.15 (0.001 ~ 0.006)
Item Unit
Model
F80 F100