Checking The Spark Plug; Checking The Thermostat - Yamaha F50D Servise Manual

Checking the spark plug

1. Disconnect the spark plug caps and
remove the spark plugs.
2. Clean the electrodes 1 with a spark plug
cleaner or wire brush.
3. Check the spark plug. Replace if the
electrodes are eroded, there is excessive
carbon or other deposits, or if the gasket
is damaged.
4. Check the spark plug gap a. Adjust the
spark plug gap if out of specification.
Specified spark plug: DPR6EB-9 (NGK)
Spark plug gap a:
0.8–0.9 mm (0.031–0.035 in)
5. Install the spark plugs, tighten them tem-
porarily, and then tighten them to the
specified torque using a spark plug
wrench.
Spark plug: 18 N·m (1.8 kgf·m, 13.3 ft·lb)
6. Connect the spark plug caps.

Checking the thermostat

1. Remove the cover 1, thermostat cover
2 and thermostat 3. NOTICE: Do not
reuse the gasket 4, always replace it
with a new one.
1
2. Suspend the thermostat in a container of
water.
3. Place a thermometer in the water and
slowly heat the water.
a
4. Measure the thermostat valve opening a
at the specified water temperatures.
Replace the thermostat if out of specifi-
cation.
General periodic maintenance
3 4
1
0
1
2
2
3
4
5
6
7
8
9
10
A
10-20