1D-2 Engine Mechanical:
Diagnostic Information and Procedures
Engine Mechanical Symptom Diagnosis
B931H21404001
Refer to “Engine Symptom Diagnosis: in Section
1A”.
Compression Pressure Check
B931H21404002
The compression pressure reading of a cylinder is a
good indicator of its internal condition.
Periodic maintenance records kept at your dealership
should include compression readings for each
maintenance service.
NOTE
• Before checking the engine for
compression pressure, make sure that the
cylinder head nuts are tightened to the
specified torque values and the valves are
properly adjusted.
• Make sure that the battery is in fully-
charged condition.
1) Warm up the engine.
2) Remove the seat. Refer to “Seat Removal and
Installation: in Section 9D”.
3) Disconnect the fuel pump relay coupler (1).
4) Remove the spark plug. Refer to “Spark Plug Cap
and Spark Plug Removal and Installation: in
Section 1H”.
5) Install the compression gauge and adaptor in the
spark plug hole. Make sure that the connection is
tight.
Special tool
(A): 09915–64512 (Compression gauge)
(B): 09913–10750 (Compression gauge
adapter)
6) Keep the throttle grip in the fully-opened position.
7) Press the starter button and crank the engine for a
few seconds. Record the maximum gauge reading
as the cylinder compression.
Compression pressure specification
Low compression pressure can indicate any of
the following conditions:
• Excessively worn cylinder wall
• Worn piston or piston rings
• Piston rings stuck in grooves
• Poor valve seating
• Ruptured or otherwise defective cylinder head
gasket
8) After checking the compression pressure, reinstall
the removed parts.
9) After connecting the fuel pump relay coupler, clear
the DTC using SDS tool. Refer to “Use of SDS
Diagnosis Reset Procedures: in Section 1A”.
1
I931H1140002-01
Standard
Approx. 1 000 kPa
(10.0 kgf/cm
2
, 142 psi)
(Automatic decompression actuated)
(A)(A)
(B)
I931H1140003-01
I931H1140004-01
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