Yamaha XJR1300 (L) '99, Service Manual

Page: 73 / 338

3-15
CHK
ADJ
MEASURING THE COMPRESSION PRESSURE
CAUTION:
3. Disconnect:
S
spark plug cap
4. Remove:
S
spark plug
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.
5. Install:
S
compression gauge 1
S
adapter 2
Compression gauge
90890-03081
Adapter
90890-04082
6. 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.
S
Refer to the following table.
Compression pressure
(With oil applied into cylinder)
Reading Diagnosis
Higher than
without oil Piston wear or damage
Repair.
Same as
without oil
Piston ring(-s), valves, cyl-
inder head gasket
or piston possibly defec-
tive
Repair.
Compression pressure (at
sea level)
Compression pressure (at sea lev-
el):
Standard:
1,050 kPa (10.5 kg / cm
2
,
10.5 bar) / 400 r / min.
Minimum:
900 kPa (9.0 kg / cm
2
,
9.0 bar) / 400 r / min.
Maximum:
1,200 kPa (12.0 kg/cm
2
,
12.0 bar) / 400 r / min.