Diagnostic Information And Procedures; Engine Mechanical Symptom Diagnosis; Compression Pressure Check - Suzuki GSF650A Service Manual

1D-4 Engine Mechanical:

Engine Mechanical Symptom Diagnosis

Refer to "Engine Symptom Diagnosis in Section 1A
(Page 1A-9)".

Compression Pressure Check

The compression pressure reading of a cylinder is a
good indicator of its internal condition.
The decision to overhaul the cylinder is often based on
the results of a compression test. 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 fuel tank. Refer to "Fuel Tank Removal
and Installation in Section 1G (Page 1G-9)".
3) Remove the frame head covers, left and right.
(GSF650) Refer to "Exterior Parts Removal and
Installation (GSF650/S/A/SAK7) in Section 9D
(Page 9D-6)".
4) Remove all the spark plugs. Refer to "Ignition Coil /
Plug Cap and Spark Plug Removal and Installation in
Section 1H (Page 1H-3)".
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): 09915–63311 (Compression gauge
attachment)
(A)

Diagnostic Information and Procedures

B817H21404001
B817H21404002
(B)
I717H1140001-01
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.
8) Repeat this procedure with the other cylinders.
Compression pressure specification
Standard
1 200 – 1 600 kPa
(12 – 16 kgf/cm 2 , (9 kgf/cm
171 – 226 psi)
Low compression pressure can indicate any of
the following conditions:
• Excessively worn cylinder walls
• Worn piston or piston rings
• Piston rings stuck in grooves
• Poor valve seating
• Ruptured or otherwise defective cylinder head
gasket
Overhaul the engine in the following cases:
• Compression pressure in one of the cylinders is
900 kPa (9 kgf/cm 2 , 128 psi) and less.
• The difference in compression pressure between
any two cylinders is 200 kPa (2 kgf/cm
and more.
• All compression pressure readings are below 1
200 kPa (12 kgf/cm
measure 900 kPa (9 kgf/cm
9) After checking the compression pressure, reinstall
the removed parts.
I717H1140005-01
Limit Difference
900 kPa 200 kPa
2 , 128 (2 kgf/cm
psi) psi)
2 , 124 psi)
2 , 171 psi) even when they
2 , 128 psi) and more.
2 , 28