Yamaha YJ125S Service Manual page 20

Timing chain
Model/number of links
Tensioning system
Valve, valve seats, valve guides
Valve clearance (cold)
Intake
Exhaust
Valve dimensions
A
Head Diameter
Valve head diameter A
Intake
Exhaust
Valve face width B
Intake
Exhaust
Valve seat width C
Intake
Exhaust
Valve margin thickness D
Intake
Exhaust
Valve stem diameter
Intake
Exhaust
Valve guide inside diameter
Intake
Exhaust
Valve stem to valve guide clearance
Intake
Exhaust
Valve stem runout
Valve seat width
Intake
Exhaust
ENGINE SPECIFICATIONS
Item
B
Face Width
Standard
Morse 92RH2005 / 88
Automatic
0.08~0.12 mm
0.13~0.17 mm
C
Seat Width
23.9~24.1 mm
20.9~21.1 mm
1.69~2.40 mm
1.69~2.40 mm
0.9~1.1 mm
0.9~1.1 mm
0.85~1.15 mm
0.85~1.15 mm
4.475~4.490 mm
4.460~4.475 mm
4.500~4.512 mm
4.500~4.512 mm
0.010~0.037 mm
0.025~0.057 mm
...
0.9~1.1 mm
0.9~1.1 mm
2-5
SPEC
Limit
...
...
...
...
D
Margin Thickness
...
...
...
...
1.6mm
1.6mm
...
...
4.445 mm
4.430 mm
4.550 mm
4.550 mm
0.080 mm
0.100 mm
0.010 mm
1.6mm
1.6mm