Yamaha F50D Servise Manual - page 355

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A

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.

5.

Install the spark plugs, tighten them tem-

porarily, and then tighten them to the

specified torque using a spark plug

wrench.

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.

2.

Suspend the thermostat in a container of

water.

3.

Place a thermometer in the water and

slowly heat the water.

4.

Measure the thermostat valve opening 

a

at the specified water temperatures.

Replace the thermostat if out of specifi-

cation.

Specified spark plug: DPR6EB-9 (NGK)

Spark plug gap 

a

:

0.8–0.9 mm (0.031–0.035 in)

Spark plug: 18 N·m (1.8 kgf·m, 13.3 ft·lb)

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a

1

2

3 4

General periodic maintenance