Measuring The Compression Pressure - Yamaha Star XVS950A 2009 Service Manual

Cylinder head nut
1st: 15 Nm (1.5 m·kgf, 11 ft·lbf)
2nd: 25 Nm (2.5 m·kgf, 18
ft·lbf)
Final: 65 Nm (6.5 m·kgf, 47
ft·lbf)
Cylinder head bolt
13 Nm (1.3 m·kgf, 9.4 ft·lbf)
TIP
• Lubricate the cylinder head nuts and wash-
ers with engine oil.
• Tighten the cylinder head nuts in the proper
tightening sequence as shown and torque
them in three stages.
A. Front cylinder head
B. Rear cylinder head
2. Install:
• Rear exhaust pipe joint
• Rear exhaust pipe joint cover
Rear exhaust pipe joint nut
15 Nm (1.5 m·kgf, 11 ft·lbf)
Rear exhaust pipe joint cover
bolt
7 Nm (0.7 m·kgf, 5.1 ft·lbf)
TIP
Tighten the rear exhaust pipe joint nuts, and
then install the rear exhaust pipe joint cover
and bolts.
EAS20710
MEASURING THE COMPRESSION PRES-
SURE
The following procedure applies to all of the
cylinders.
TIP
Insufficient compression pressure will result in
a loss of performance.
1. Measure:
• Valve clearance
Out of specification → Adjust.
Refer to "ADJUSTING THE VALVE
CLEARANCE" on page 3-5.
2. Start the engine, warm it up for several
minutes, and then turn it off.
3. Remove:
• Rear cylinder right plastic cover
Refer to "ENGINE REMOVAL" on page 5-
1.
4. Disconnect:
• Spark plug caps
5. Remove:
• Spark plug
ECA13340
Before removing the spark plugs, use com-
pressed air to blow away any dirt accumu-
lated in the spark plug wells to prevent it
from falling into the cylinders.
6. Install:
• Compression gauge "1"
• Extension "2"
Compression gauge
90890-03081
Engine compression tester
YU-33223
Extension
90890-04136
Extension
90890-04082
TIP
Use "extension : 90890-04136" for front cylin-
der and "extension : 90890-04082" for rear cyl-
inder.
5-23
CYLINDER HEADS