Yamaha F150A, Service Manual, Page: 226 / 493

7-1
Power unit (check and adjustment)
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Power unit (check and
adjustment)
Checking the compression pressure
1. Start the engine, warm it up for 5 min-
utes, and then stop it.
2. Remove the clip from the engine shut-off
switch.
3. Disconnect the spark plug wires.
4. Remove all of the spark plugs, and then
install the special service tools “1” and
“2” into the spark plug hole.
5. Fully open the throttle.
6. Crank the engine until the reading on the
compression gauge stabilizes, and then
measure the compression pressure.
7. Remove the special service tools “1” and
“2”.
8. Install all of the spark plugs, and then
tighten the spark plugs to the specified
torque.
9. Connect the spark plug wires.
Checking the oil pressure
1. Connect the YDIS to display “Oil pres-
sure”.
2. Start the engine and warm it up until the
engine idle speed stabilizes at
650–750 r/min.
3. Measure the oil pressure.
Checking the valve clearance
• Measure the valve clearances when the
engine is cold.
• Cover the fuel components using a rag to
prevent fuel from spilling out.
Do not turn the flywheel magnet counter-
clockwise. Otherwise, the water pump
impeller could be damaged.
1. Reduce the fuel pressure. See “Reducing
the fuel pressure” (6-5).
2. Disconnect the fuel hoses “1” and “2”.
3. Remove the fuel pump assemblies. See
“Removing the fuel pump assembly” (6-
13).
Compression gauge “1”: 90890-03160
Compression gauge extension “2”:
90890-06563
Minimum compression pressure
(reference data):
880.0 kPa (8.80 kgf/cm
2
, 127.6 psi)
at 20 °C (68 °F)
Spark plug: 25 N·m (2.5 kgf·m, 18.4 ft·lb)
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Oil pressure (reference data):
320.0 kPa (3.20 kgf/cm 2 , 46.4 psi)
at 60 °C (140 °F) with SL 10W-30
engine oil and at 700 r/min
500.0 kPa (5.00 kgf/cm
2 , 72.5 psi)
at 62 °C (144 °F) with SL 10W-30
engine oil and at 3000 r/min
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