Compression Pressure - HYOSUNG TE 450 Service Manual

COMPRESSION PRESSURE

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 pressure reading for each maintenance
service.
Compression pressure
Standard
Service limit
▣ ▣ COMPRESSION TEST PROCEDURE
NOTE
� � Before testing the engine for compression
pressure, make sure that the cylinder head
nuts are tightened to the specified torque val-
ues and valves are properly adjusted.
� � Have the engine warmed up by idling before
testing.
� � Make sure that the battery is fully-charged con-
dition.
Remove the related parts and test the compression
pressure in the following manner.
WARNING
The hot radiator and the hot engine can burn you.
Wait until the radiator and the engine are cool
enough to touch.
● Remove the spark plug.
● Fit the compression gauge in the plug holes.
Make sure that the connection is tightened.
● Keep the throttle lever in full-open position.
● Press the starter switch and crank the engine for a
few seconds.
Record the maximum gauge reading as the com-
pression of cylinder.
Compression gauge : 09915-64511
2
16 kg/cm (at 500 rpm)
2
14 kg/cm (at 500 rpm)
PERIODIC MAINTENANCE 2-24
Low compression pressure can indicate some of the
following conditions :
● Excessively worn cylinder wall
● Worn-down piston or piston rings
● Piston rings stuck in grooves
● Poor seating of valves
● Ruptured or otherwise defective cylinder head
gasket
NOTE
When the compression pressure goes below
specification, check the engine for conditions list-
ed above.