Yamaha F4A - Page 44

2-4
SPEC
MAINTENANCE SPECIFICATIONS
Item Unit
Model
F4A/F4
Stem outside diameter
Intake mm (in) 5.475~5.490 (0.2156~0.2161)
Exhaust mm (in) 5.460~5.475 (0.2150~0.2156)
Guide inside diameter mm (in) 5.500~5.512 (0.2165~0.2170)
Stem to guide clearance
Intake mm (in) 0.010~0.037 (0.0004~0.0015)
Exhaust mm (in) 0.025~0.052 (0.0010~0.0020)
Stem runout limit mm (in) 0.03 (0.0012)
VALVE SPRING
Free length mm (in) 35.0 (1.38)
Free length limit mm (in) 34.0 (1.34)
Set length mm/kg (in/lb) 21.6/7.2 (0.85/15.87)
Tilt limit mm (in) 1.2 (0.05)
PISTON
Piston-to-cylinder clearance mm (in) 0.035~0.065 (0.0014~0.0026)
Piston diameter (D)
Standard mm (in) 58.950~58.965 (2.3209~2.3215)
Measuring point (H) mm (in) 10 (0.39)
Pin boss inside diameter mm (in) 13.009~13.017 (0.5122~0.5125)
Oversize piston diameter
1st* mm (in) 59.25 (2.333)*
1
Except for USA
2nd mm (in) 59.50 (2.343)
PISTON PIN
Outside diameter mm (in) 12.995~13.000 (0.5116~0.5118)
PISTON RINGS
Top ring
Type Plain
Dimensions (BxT) mm (in) 1.5 x 2.6 (0.06 x 0.10)
End gap (installed) mm (in) 010~020 (0.004~0.008)
Wear limit mm (in) 0.40 (0.016)
Side clearance (installed) mm (in) 0.04~0.08 (0.002~0.003)
2nd ring
Type Plain
Dimensions (BxT) mm (in) 1.5 x 2.6 (0.06 x 0.10)
End gap (installed) mm (in) 0.25~0.40 (0.010~0.016)
Ware limit mm (in) 0.60 (0.024)
Side clearance (installed) mm (in) 0.02~0.06 (0.001~0.002)