Yamaha 25BMH, Service Manual

Page: 230 / 446

CYLINDER HEAD
5-23
E
POWR
CHECKING THE THERMOSTAT
1. Check:
• Thermostat
Damage/stick
→
Replace.
2. Measure:
• Valve opening temperature
• Valve lift
Out of specification
→
Replace.
Measuring steps
(1) Suspend the thermostat in a container
filled with water.
(2) Place a thermometer in the water.
(3) Slowly heat the water.
(4) While stirring the water, check that the
thermostat opens at the specified tem-
perature.
W
W W
Wa
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m m
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V V
Va
a a
allllve
ve ve
ve li
li li
lifffftttt
B B B Be e e ellllo o o ow w w w 48 48 48 48 – – – – 52 52 52 52°°°°C C C C
((((1
1 1
11
1 1
18
8 8
8 –
– –
– 1
1 1
12
2 2
26
6 6
6°°°°F
F F
F))))
0 0 0 0 mm mm mm mm
((((0
0 0
0 iiiin
n n
n))))
A A A Ab b b bo o o ov v v ve 60 e 60 e 60 e 60°°°°C C C C
((((1
1 1
140
40 40
40°°°°F
F F
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M M M Miiiin n n n. . . . 3 3 3 3 m m m mm m m m
((((0
0 0
0....1
1 1
12
2 2
2 iiiin
n n
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