Yamaha F4B, Руководство по обслуживанию

Страница: 128 / 202

7-35
POWR
Power unit
• If the valve seat contact area is too narrow
and situated near the bottom edge of the
valve face, cut the bottom edge of the valve
seat using a 60° cutter to center the area,
and then set its width using a 45° cutter.
b
Previous contact width
7. After refacing the contact width of the
valve seat to specification, apply a thin,
even layer of lapping compound onto the
valve seat, and then lap the valve using
the special service tool
a
. NOTICE: Do
not get the lapping compound on the
valve stem and valve guide.
8. Recheck the valve seat contact area of
the valve. See “Checking the valve seat”
(7-32).
Checking the spark plug
1. Clean the electrodes
a
using a spark
plug cleaner.
2. Check the spark plug. Replace if the
electrodes are eroded, there is carbon or
other deposits.
3. Check the spark plug gap
b
. Replace if
out of specification.
Checking the thermostat cover
anode
1. Check the anode. Replace if eroded.
Clean if there is grease, oil, or scales.
NOTICE: Do not apply grease, oil, or
paint to the anode.
Checking the thermostat
1. Suspend the thermostat in a container of
water.
2. Place a thermometer in the water and
slowly heat the water.
Valve lapper
a
: 90890-04101
60˚
b
a
Specified spark plug: CR6HSB (NGK)
Spark plug gap
b
:
0.6–0.7 mm (0.024–0.028 in)
a
b