Yamaha 2002 YFA1 Supplementary Service Manual page 12

Inside diameter (valve guide)
Intake
Exhaust
Stem-to-guide clearance
Intake
Exhaust
Stem runout limit
Valve seat width
Intake
Exhaust
Piston:
Piston size "D"
Measuring point "H"
Piston-to-cylinder clearance
<Wear limit>
Over size 2nd
4th
Piston off-set
Piston off-set direction
Inside diameter (piston pin bore)
Outside diameter (piston pin)
Piston pin-to-piston clearance
<Limit>
Piston ring:
Type
Top ring
2nd ring
Dimension (B × T)
Top ring
Second ring
Oil ring
End gap (installed)
Top ring
Second ring
Oil ring
MAINTENANCE SPECIFICATIONS
Model
D
T
B
T
B
T
5.000 ~ 5.012 mm (0.197 in)
5.000 ~ 5.012 mm (0.197 in)
0.010 ~ 0.037 mm (0.004 ~ 0.0014 in)
0.025 ~ 0.052 mm (0.0010 ~ 0.0020 in)
0.01 mm (0.0004 in)
0.9 ~ 1.1 mm (0.035 ~ 0.043 in)
0.9 ~ 1.1 mm (0.035 ~ 0.043 in)
48.96 ~ 49.00 mm (1.927 ~ 1.929 in)
6 mm (0.24 in)
From bottom of the piston.
H
0.020 ~ 0.040 mm (0.0008 ~ 0.0016 in)
<0.15 mm (0.006 in)>
49.5 mm (1.95 in)
50.0 mm (1.97 in)
0.5 mm (0.02 in)
Intake side
13.002 ~ 13.013 mm (0.5119 ~ 0.5123 in)
12.996 ~ 13.000 mm (0.5117 ~ 0.5118 in)
0.002 ~ 0.017 mm (0.0001 ~ 0.0006 in)
<0.07 mm (0.003 in)>
Barrel
Taper
B
1.0 × 2.0 mm (0.039 × 0.079 in)
1.0 × 2.0 mm (0.039 × 0.079 in)
2.0 × 2.2 mm (0.079 × 0.087 in)
0.15 ~ 0.30 mm (0.006 ~ 0.012 in)
0.15 ~ 0.30 mm (0.006 ~ 0.012 in)
0.20 ~ 0.80 mm (0.008 ~ 0.031 in)
– 4 –
SPEC
YFA1 (P) 2002