Inspecting Idle Speed; Changing Engine Oil - Yamaha LF250 Owner's Manual

1. Spark plug gap
2. Spark plug part number
3. Spark plug I.D. mark (NGK)
Spark plug gap:
1.0–1.1 mm (0.039–0.043 in)
To install the spark plug
1. Wipe off any dirt from the threads, insu-
lator, and gasket surface of the spark
plug.
2. Install the spark plug, and then tighten it
to the specified torque.
Spark plug tightening torque:
25 Nm (2.55 kgf-m, 18.4 ft-lb)
TIP:
If a torque-wrench is not available when you
are reinstalling a spark plug, a good estimate
of the correct torque is 1/12 turn past finger-
tight. When you are installing a new spark
plug, a good estimate of the correct torque is
1/2 to 2/3 turn past finger-tight.
3. Install the ignition coil, and then tighten
the bolts to the specified torque.
Bolt tightening torque:
7 Nm (0.71 kgf-m, 5.2 ft-lb)
4. Install the ECM (Electronic control mod-
ule) cover and tighten the bolts to the
specified torque.
Bolt tightening torque:
8 Nm (0.82 kgf-m, 5.9 ft-lb)
EMU29045

Inspecting idle speed

EWM00452
WARNING
 Do not touch or remove electrical parts
when starting or during operation.
 Keep hands, hair, and clothes away
from the flywheel and other rotating
parts while the engine is running.
ECM00491
NOTICE
This procedure must be performed while
the outboard motor is in the water. A flush-
ing attachment or test tank can be used.
If the boat is not equipped with a tachometer
for the outboard motor, use a diagnostic ta-
chometer for this procedure. Results may
vary depending on whether testing is con-
ducted with the flushing attachment, in a test
tank, or with the outboard motor in the water.
1. Start the engine and allow it to warm up
fully in neutral until it is running smoothly.
2. Once the engine has warmed up, verify
whether the idle speed is set to specifi-
cation. For idle speed specifications, see
page 15. If you have difficulty verifying
the idle speed, or the idle speed requires
adjustment, consult a Yamaha dealer or
other qualified mechanic.
EMU37487

Changing engine oil

EWM00761
WARNING
 Avoid draining the engine oil immediate-
ly after stopping the engine. The oil is
hot and should be handled with care to
avoid burns.
Maintenance
83