PERIODIC
MAINTENANCE 2-23
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 mainte-
nance records kept at your dealership should include compression readings for each maintenance service.
WM Compression pressure:
Standard: 800 kPa (8.0 kgf/cm
2
,114 psi)
(Automatic decompression actuated)
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
NOTE:
When the compression pressure
goes
below specification, check the engine for conditions listed above.
COMPRESSION
TEST
PROCEDURE
NOTE:
• Before testing the engine for compression pressure, make
sure
that
the cylinder head nuts are tightened to the speci-
fied torque values and the valves are properly adjusted.
• Warm up the engine before testing.
• Make sure
that
the battery is
fully
charged.
Remove
the related parts and
test
the compression pressure
in
the
following manner.
•
Remove
the spark plug.
2-6)
•
Install
the compression gauge and adaptor in the spark plug
hole.
Make sure that the connection is
tight.
•
Keep the
throttle
lever in the fully open position.
•
Press the starter button and crank the engine for
a
few sec-
onds. Record
the
maximum gauge reading
as
the cylinder
compression.
09915-64510:
Compression gauge set
09915-63310:
Adaptor
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