Yamaha F15MHX Manuel D'entretien page 150

INSP
ADJ
GENERAL
6. Measure:
9 Compression pressure
Too high
valve surfaces and piston crown for
carbon deposits.
Too low
the affected cylinder and measure
again.
Refer to the following table.
Compression pressure:
961 kPa (9.8 Kg/cm
Compression pressure
(With oil applied into cylinder)
Reading
Higher than
without oil
Same as
without oil
Measurement steps:
8 Crank the engine with the throttle wide-
open until the reading on the compres-
sion gauge stabilizes.
w
Before cranking the engine, ground all
spark plug leads to prevent sparking.
7. Install:
9 Spark plug
3-20
Inspect the cylinder head,
Squirt a few drops of oil into
2 , 139.4 psi)
Diagnosis
Worn or damaged pistons
Replace.
Possible defective ring(s), val-
ves, cylinder head gasket or
piston Repair.
E