Yamaha F90D, Service Manual

Page: 93 / 241

POWR
Power unit
5-27
6D81G11
6. Remove the intake and exhaust valves.
NOTE:
Be sure to keep the valves, springs, and
other parts in the order as they were
removed.
Checking the valve lifters
1. Check the valve lifters for damage,
scratches, or wear. Replace if necessary.
Checking the valve springs
1. Measure the valve spring free length
a
.
Replace if below specification.
2. Measure the valve spring tilt
b
. Replace
if above specification.
Checking the valves
1. Check the valve face for pitting or wear.
Replace if necessary.
2. Measure the valve margin thickness
a
.
Replace if out of specification.
3. Measure the valve stem diameter
b
.
Replace if out of specification.
Valve spring compressor
8
:
YM-01253
Valve spring compressor attachment
9
:
YB-06320
Valve spring free length
a
:
53.20 mm (2.0945 in)
Valve spring tilt limit
b
:
2.6 mm (0.10 in)
Valve margin thickness
a
:
Intake:
0.80–1.20 mm
(0.0315–0.0472 in)
Exhaust:
1.00–1.40 mm
(0.0394–0.0551 in)