Honda CBR125R, Owner'S Manual

Page: 194 / 430

CYLINDER HEAD/VALVES
8-6
CYLINDER COMPRESSION
Warm the engine to normal operating temperature.
Stop the engine.
Remove the spark plug (page 3-9).
Install the compression gauge attachment into the
spark plug hole.
Connect the compression gauge to the attachment.
Turn the ignition switch ON (and engine stop switch
" ": CM and U type).
Shift the transmission into neutral.
Crank the engine with the starter motor.
Open the throttle all the way and crank the engine
with the starter motor until the gauge reading stops
rising.
Low compression can be caused by:
– Blown cylinder head gasket
– Improper valve adjustment
– Valve leakage
– Worn piston ring or cylinder
High compression can be caused by:
– Carbon deposits in combustion chamber or on
piston head
CYLINDER HEAD COVER
REMOVAL
Remove the middle cowl (page 2-9).
Remove the radiator lower mounting bolt, then
move the radiator forward.
TOOL:
Compression gauge attachment 07RMJ-MY50100
or equivalent com-
mercially available
To avoid discharging
the battery, do not
operate the starter
motor for more
than 7 seconds.
STANDARD:
1,343 kPa (13.7 kgf/cm
2
, 195 psi) at 530 min
-1
(rpm)
COMPRESSION GAUGE
COMPRESSION GAUGE ATTACHMENT
The cylinder head
cover can be
serviced with the
engine installed in
the frame.
BOLT RADIATOR