Changing Engine Oil; Checking Oil Pressure; Adjusting Engine Idling Speed - Yamaha YZ450F Owner's Service Manual

CHANGING THE ENGINE OIL
1. Start the engine and let it warm up
for several minutes.
2. Stop the engine and place an oil
pan under the drain bolt.
3. Remove:
• Oil filler cap "1"
• Drain bolt (with gasket) "2"
• Drain bolt (with gasket) "3"
Drain the engine oil.
4. If the oil filter is to be replaced dur-
ing this oil change, remove the fol-
lowing parts and reinstall them.
Replacement steps:
a. Remove the oil filter element cov-
er "1" and oil filter element "2".
b. Check the O-rings "3", if cracked
or damaged, replace them with a
new one.
c. Install the oil filter element and oil
filter element cover.
Oil filter element cover:
10 Nm (1.0 m•kg, 7.2
ft•lb)
5. Install:
• Gaskets
• Oil drain bolt (oil pan)
Oil drain bolt (oil pan):
20 Nm (2.0 m•kg, 14
ft•lb)
• Oil drain bolt (oil tank)
Oil drain bolt (oil tank):
20 Nm (2.0 m•kg, 14
ft•lb)
6. Fill:
• Engine oil
Oil quantity:
Periodic oil change:
0.95 L (0.84 Imp qt,
1.00 US qt)
With oil filter replace-
ment:
1.0 L (0.88 Imp qt, 1.06
US qt)
Total amount:
1.2 L (1.06 Imp qt, 1.27
US qt)
7. Install:
• Oil filler cap
8. Inspect:
• Engine (for oil leaks)
• Oil level
CHECKING THE OIL PRESSURE
1. Check:
• Oil pressure
Checking steps:
a. Slightly loosen the oil pressure
check bolt "1".
b. Start the engine and keep it idling
until oil starts to seep from the oil
pressure check bolt. If no oil
comes out after one minute, turn
the engine off so it will not seize.
c. Check oil passages and oil pump
for damage or leakage.
d. Start the engine after solving the
problem(s) and recheck the oil
pressure.
e. Tighten the oil pressure check
bolt.
Oil pressure check bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
3-10
ENGINE
ADJUSTING THE ENGINE IDLING
SPEED
• Because the air pressure is lower at
high altitudes, the air-fuel mixture
will become richer. If the engine
idling speed is low, turn the starter
(choke) knob/idling screw a few
clicks counterclockwise to increase
the idling speed.
• Before adjusting the engine idling
speed, make sure that the com-
pression pressure is within specifi-
cation and that the air filter element
is not clogged.
• Adjust the engine idling speed with
the starter (choke) knob/idling
screw pushed in completely.
1. Start the engine and warm it up
until the engine oil has reached
the specified temperature.
2. Use a temperature probe tester
"1" and contact it to the drain bolt
thread.
Oil temperature:
55.0–65.0 °C
(131–149°F)
3. Adjust:
• Engine idling speed
Adjustment steps:
a. Turn the starter knob/idle screw
"1" until the specified engine idling
speed is obtaind.
Using the digital tachometer, mea-
sure the engine speed with the detec-
tor "c" pinched in the high tension
cord "2" of the ignition coil.
Digital tachometer:
YU-39951-B/90890-
06760
To increase the engine idling
speed → Turn the starter
(choke) knob/idling screw
counterclockwise "a".
To decrease the engine idling
speed → Turn the starter
(choke) knob/idling screw
clockwise "b".