Compression Pressure Check - HYOSUNG RT 125 D Service Manual

2-19 PERIODIC MAINTENANCE
COMPRESSION PRESSURE
CHECK
The compression 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 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
bolts are tightened to the specified torque
values and valves are properly adjusted.
Have the engine warmed up by idling before
testing.
Be sure that the battery used is in fully-
charged condition.
Remove the related parts and test the compression
pressure in the following manner :
● Remove the spark plug.
WARNING
The hot engine can burn you.
Wait until the engine are cool enough to touch.
● Fit the compression gauge in the spark plug hole.
Make sure that the connection is tightened.
● Keep the throttle grip in the full-opened position.
● Press the starter switch and crank the engine for a
few seconds. Record the maximum gauge reading
as the cylinder compression.
Compression gauge : 09915-64511
14 ~ 16 kgf/㎠
12 kgf/㎠
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 valve seating
● Ruptured or otherwise defective cylinder head
gasket
NOTE
When the compression pressure goes below
specification, check the engine for conditions
listed above.