Yamaha RX10H Service Manual page 35

COMPRESSION PRESSURE MEASUREMENT
CAUTION:
Before removing the spark plugs, use com-
pressed air to blow away any dirt accumu-
lated in the spark plug wells to prevent it
from falling into the cylinders.
4. Install:
S Compression gauge 1
Compression gauge set
90890-03081, YU-33223
Compression gauge adapter
90890-04136, YU-33223-3
5. Measure:
S Compression pressure
Above the maximum pressure ! Inspect the
cylinder head, valve surfaces, and piston
crown for carbon deposits.
Below the minimum pressure ! Squirt a few
drops of oil into the affected cylinder and
measure again.
Refer to the following table.
Compression pressure
(with oil applied into cylinder)
Reading
Higher than
without oil
Same as
without oil
Compression pressure
(at sea level):
Standard:
1,450 kPa (14.5 kg/cm
206 psi) at 400 r/min
Minimum:
1,260 kPa (12.6 kg/cm
179 psi) at 400 r/min
Maximum:
1,620 kPa (16.2 kg/cm
230 psi) at 400 r/min
2-19
INSP
ADJ
Diagnosis
Piston ring(-s) wear or
damage ! Repair.
Piston, valves, cylinder
head gasket or piston
possibly defective !
Repair.
Compression pressure
(at sea level)
2
,
2
,
2
,