Yamaha 2007 XP500 - Measuring the Compression Pressure

ENGINE
3-11
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a. Start the engine, warm it up for several min-
utes, and then let it run at the specified en-
gine idling speed.
b. Check that the stationary pointer “a” is within
the firing rang “b” on the A.C. magneto.
Incorrect firing range → Check the ignition
system.
NOTE:
The ignition timing is not adjustable.
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5. Install:
● Timing plug
6. Install:
● Left footrest board
● Side cover (left and right)
● Center cover
Refer to “GENERAL CHASSIS” on page 4-1.
EAS20710
MEASURING THE COMPRESSION
PRESSURE
The following procedure applies to all of the cyl-
inders.
NOTE:
Insufficient compression pressure will result in a
loss of performance.
1. Remove:
● Footrest board (left and right)
● Inner fender
Refer to “GENERAL CHASSIS” on page 4-1.
2. Measure:
● Valve clearance
Out of specification → Adjust.
Refer to “ADJUSTING THE VALVE CLEAR-
ANCE” on page 3-3.
3. Start the engine, warm it up for several min-
utes, and then turn it off.
4. Disconnect:
● Spark plug cap
5. Remove:
● Spark plug
CAUTION:
ECA13340
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.
6. Install:
● Compression gauge “1”
7. Measure:
● Compression pressure
Out of specification → Refer to steps (c) and
(d).
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a. Set the main switch to “ON”.
Engine idling speed
1100–1300 r/min
Timing plug
8 Nm (0.8 m•kg, 5.8 ft•lb)
a
b
T
R
.
.
Compression gauge
90890-03081
Engine compression tester
YU-33223
Extension
90890-04082
Standard compression pressure
(at sea level)
1400 kPa/360 r/min (199.1 psi/
360 r/min) (14.0 kgf/cm
2
/360 r/
min)
Maximum compression pressure
1570 kPa/360 r/min (223.3 psi/
360 r/min) (15.7 kgf/cm
2
/360 r/
min)
Minimum compression pressure
1200 kPa/360 r/min (170.7 psi/
360 r/min) (12.0 kgf/cm
2
/360 r/
min)
1