Engine Inspection; Measure The Compression Pressure - Yamaha 2014 MT-07 Service Manual

EAS20041

ENGINE INSPECTION

EAS30249

MEASURE THE COMPRESSION PRESSURE

The following procedure applies to all of the cyl-
inders.
TIP
Insufficient compression pressure will result in a
loss of performance.
1. Measure:
• Valve clearance
Out of specification → Adjust.
Refer to "ADJUSTING THE VALVE CLEAR-
ANCE" on page 3-5.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Remove:
• Rider seat
Refer to "GENERAL CHASSIS (1)" on page
4-1.
• Fuel tank top cover
• Fuel tank cover (left)
• Fuel tank cover (right)
• Fuel tank center cover
• Fuel tank front cover
Refer to "GENERAL CHASSIS (4)" on page
4-11.
• Fuel tank
Refer to "FUEL TANK" on page 7-1.
4. Disconnect:
• Ignition coil couplers "1"
5. Remove:
• Ignition coils "2"
6. Remove:
• Spark plugs
ECA13340
NOTICE
Before removing the spark plugs, use com-
pressed air to blow away any dirt accumulat-
ed in the spark plug wells to prevent it from
falling into the cylinders.
7. Install:
• Extension "1"
• Compression gauge "2"
8. Measure:
• Compression pressure
TIP
Due to the engine characteristics, the compres-
sion pressure is different for cylinder #1 and cyl-
inder #2.
1
2
▼ ▼▼▼
a. Turn the main switch to "ON".
b. With the throttle wide open, crank the engine
5-1
ENGINE INSPECTION
Extension
90890-04136
Compression gauge
90890-03081
Engine compression tester
YU-33223
2
Out of specification → Refer to steps (c) and
(d).
Standard compression pressure
(at sea level)
#1 880 kPa/355 r/min (8.8
kgf/cm²/355 r/min, 125.2 psi/355
r/min)
#2 790 kPa/355 r/min (7.9
kgf/cm²/355 r/min, 112 psi/355
r/min)
Minimum–maximum
#1 770–990 kPa/355 r/min (7.7–
9.9 kgf/cm²/355 r/min, 109.5–
140.8 psi/355 r/min)
#2 690–880 kPa/355 r/min (6.9–
8.8 kgf/cm²/355 r/min, 98.1–
125.1 psi/355 r/min)
▼ ▼▼▼ ▼ ▼ ▼▼▼ ▼ ▼ ▼▼▼ ▼
until the reading on the compression gauge
stabilizes.
1
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