Adjusting Pilot Screw; Adjusting Engine Idling Speed; Checking Oil Pressure - Yamaha YZ450F(X) Owner's Service Manual

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 filter drain bolt
Oil filter drain bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
• Drain bolt (right crankcase)
Drain bolt (right crank-
case):
20 Nm (2.0 m•kg, 14
ft•lb)
• Drain bolt (left crankcase)
Drain bolt (left crank-
case):
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
Refer to "ENGINE OIL LEVEL IN-
SPECTION".
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)
ADJUSTING THE PILOT SCREW
1. Adjust:
• Pilot screw "1"
Adjustment steps:
To optimize the fuel flow at a smaller
throttle opening, each machine's pilot
screw has been individually set at the
factory. Before adjusting the pilot
screw, turn it in fully and count the
number of turns. Record this number
as the factory-set number of turns
out.
a. Turn in the pilot screw until it is
lightly seated.
b. Turn out the pilot screw by the
factory-set number of turns.
Pilot screw (example):
1-1/2 turns out
3-9
ENGINE
ADJUSTING THE ENGINE IDLING
SPEED
1. Start the engine and thoroughly
warm it up.
2. Adjust:
• Engine idling speed
Adjustment steps:
a. Adjust the pilot screw.
Refer to "ADJUSTING THE PI-
LOT SCREW" section.
b. Turn the throttle stop screw "1"
until the specified engine idling
speed.
Using a digital engine tachometer for
idle speed adjustment, detect the en-
gine idling speed by bringing the
sensing element "c" of the engine ta-
chometer close to the ignition coil "2".
Digital tachometer:
YU-39951-B/90890-
06760
→
To increase idle speed
throttle stop screw "1" in "a".
To decrease idle speed
the throttle stop screw "1" out
"b".
Engine idling speed:
1,900–2,100 r/min
Turn the
→
Turn