Compression Pressure - Yamaha F15B Service Manual

Compression pressure

9 Consult this chart after the ignition and fuel systems have been checked.
Measure the compression
pressure.
Does the
pressure exceed
the specification
values?
No
Check the valve clearance.
Does the
valve clearance
specified value?
Yes
Add a small amount of engine oil
into the cylinder through the
spark plug hole.
Does the
compression
pressure
increase?
No
Check the valves, valve seat,
cylinder head gasket and cylinder
head for wear or damage.
Replace if worn or damaged.
NOTE:
While restoring a damaged part, it is also necessary to trace and solve the cause of the damage.
6D45F11
NOTE:
Since this outboard motor is equipped with an automatic decom-
pression mechanism, accurate data may be difficult to obtain due
to differences in the way the starter rope is pulled.
Yes
Check other component again.
No
Adjust the valve clearanace.
Check the piston, piston rings,
Yes
and cylinder bore for wear or
damage. Correct or replace if
worn or damaged.
Power unit
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