Yamaha MX250 User Manual

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ENGINE
3-1
ENGINE
ENGINE INSPECTION
MEASURING THE COMPRESSION PRESSURE
TIP
Measure the compression pressure after checking and
adjusting the valve clearance.
1.
Warm up the engine for several minutes.
2.
Remove:
• Spark plug cap
• Spark plug
3.
Connect:
• Compression gauge “1”
• Extension “2”
4.
Measure:
• Compression pressure
Crank the engine until the needle stop rising on the
compression gauge.
Out of specification  Refer to the testing steps.
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Testing steps (below the minimum specification):
a. Squirt a few drops of oil into the cylinder.
b. Measure the compression again.
Before removing the spark plug, use compressed air
to clean the cylinder head cover to prevent dirt from
falling into the engine.
NOTICE
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Engine compression tester:
YU-33223
Compression gauge:
90890-03081
Extension:
90890-04082
Standard compression pressure:
450–550 kPa
(4.5–5.5 kg/cm², 65.25–79.75 psi)
To prevent sparking when cranking the engine,
ground the high tension cord.
WARNING

Yamaha MX250 Specifications

General

Brand	Yamaha
Model	MX250
Category	Outboard Motor
Language	English