Compression Pressure - HYOSUNG MS3 250 Sercie Manual

COMPRESSION PRESSURE

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 mainte-
nance records kept at your dealership should include
compression reading for each maintenance service.
Compression pressure
Standard
Service limit
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 val-
ues 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.
● Support the motorcycle with the center stand.
WARNING
The hot engine can burn you. Wait until the engine
are cool enough to touch.
● Using the side cover stay, lift the front end of the
side cover and prop it up. (Refer to page 2-2)
● Remove the spark plug.
● Fit the compression gauge in the plug hole, while
taking care that the connection is tightened.
● Keep the throttle grip in full-open position.
● Crank the engine a few seconds with the starter,
and record the maximum gauge reading as the
compression of cylinder.
Compression gauge : 09915-64511
2
11 kgf/cm (at 500 rpm)
2
10 kgf/cm (at 500 rpm)
2
15 kgf/cm (at 500 rpm)
2
13 kgf/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.