Yamaha F20A Service Manual

5-26
POWR
E
CAMSHAFT AND VALVES
Rocker arm and rocker arm shaft inspection
1. Measure:
● Rocker arm inside diameter a
● Rocker arm shaft outside diameter b
Out of specification → Replace the
defective part(s).
Camshaft inspection
1. Measure:
● Camshaft lobe dimensions a and b
Out of specification → Replace the
camshaft.
Rocker arm inside diameter:
16.000 ~ 16.018 mm
(0.6299 ~ 0.6306 in)
Rocker arm shaft outside
diameter:
15.971 ~ 15.991 mm
(0.6288 ~ 0.6296 in)
Camshaft lobe dimension:
a IN: 30.884 ~ 30.984 mm
(1.2159 ~ 1.2198 in)
b IN: 25.95 ~ 26.05 mm
(1.022 ~ 1.025 in)
a EX: 30.884 ~ 30.984 mm
(1.2159 ~ 1.2198 in)
b EX: 25.95 ~ 26.05 mm
(1.022 ~ 1.025 in)
2. Measure:
● Camshaft journal diameter a
● Camshaft bearing inside diameter b
Out of specification → Replace the
camshaft.
3. Check:
● Decompression actuator
Excessive wear → Replace the cam-
shaft.
Camshaft journal diameter:
a: 36.925 ~ 36.945 mm
(1.4537 ~ 1.4545 in)
Camshaft bearing inside
diameter:
b: 37.000 ~ 37.025 mm
(1.4567 ~ 1.4577 in)

Yamaha F20A Specifications

General

Brand	Yamaha
Model	F20A
Category	Outboard Motor
Language	English