Yamaha RS90NL Supplementary Service Manual page 102

Model
Valves, valve seats, valve guides:
Valve clearance (cold)
Intake
Exhaust
Valve dimensions
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
<Limit>
Exhaust
<Limit>
Valve guide inside diameter
Intake
<Limit>
Exhaust
<Limit>
Valve-stem-to-valve-guide clearance
Intake
<Limit>
Exhaust
<Limit>
Valve stem runout limit
Valve seat width
Intake
<Limit>
Exhaust
<Limit>
MAINTENANCE SPECIFICATIONS
RS90N/RS90NR/RS90RS/RS90GT/RS90MS
0.15 ~ 0.22 mm (0.0059 ~ 0.0087 in)
0.21 ~ 0.25 mm (0.0083 ~ 0.0098 in)
29.9 ~ 30.1 mm (1.1772 ~ 1.1850 in)
25.9 ~ 26.1 mm (1.0197 ~ 1.0276 in)
A
1.90 ~ 2.62 mm (0.0748 ~ 0.1031 in)
B
1.90 ~ 2.62 mm (0.0748 ~ 0.1031 in)
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
C
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
0.8 ~ 1.2 mm (0.0315 ~ 0.0472 in)
0.5 ~ 0.9 mm (0.0197 ~ 0.0354 in)
D
4.975 ~ 4.990 mm (0.1959 ~ 0.1965 in)
4.945 mm (0.1947 in)
4.965 ~ 4.980 mm (0.1955 ~ 0.1961 in)
4.935 mm (0.1943 in)
5.000 ~ 5.012 mm (0.1969 ~ 0.1973 in)
5.050 mm (0.1988 in)
5.000 ~ 5.012 mm (0.1969 ~ 0.1973 in)
5.050 mm (0.1988 in)
0.010 ~ 0.037 mm (0.0004 ~ 0.0015 in)
0.08 mm (0.0031 in)
0.020 ~ 0.047 mm (0.0008 ~ 0.0019 in)
0.10 mm (0.0039 in)
0.01 mm (0.0004 in)
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
1.6 mm (0.0630 in)
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
1.6 mm (0.0630 in)
98
SPEC