Yamaha YZ450FP 2023, Owner'S Service Manual

Page: 91 / 388

ENGINE
3-13
EAM30254
CHECKING THE SPARK PLUG
1. Remove:
• Seat
•
Side cover (left/right)
• Shroud (left/right)
Refer to “GENERAL CHASSIS” on page 4-1.
•
Fuel tank “1”
Refer to “FUEL TANK” on page 7-1.
NOTICE
ECA24400
Do not use too much force to pull the hose.
TIP
Remove the fuel tank, turn this 180

clockwise,
and put it in the frame “2” as shown.
2. Remove:
•
Spark plug cap
• Spark plug
Refer to “CAMSHAFT” on page 5-10.
NOTICE
ECA24410
In order not to allow the dirt accumulated
around the spark plug to drop from the spark
plug hole into the cylinder, clean it before re-
moving the spark plug.
3. Check:
• Spark plug type
Wrong type

Replace.
4. Check:
• Electrode
Damage/wear

Replace the spark plug.
• Insulator
Abnormal color

Replace the spark plug.
Normal color is medium-to-light tan.
5. Clean:
• Spark plug
(with a spark plug cleaner or a wire brush)
6. Measure:
•
Spark plug gap “a”
Out of specification

Adjust the spark plug
gap.
7. Install:
•
Spark plug
TIP
Before installing the spark plug, clean the spark
plug and gasket surface.
8. Install:
• Spark plug cap
•
Fuel tank
• Shroud (left/right)
•
Side cover (left/right)
• Seat
Refer to “GENERAL CHASSIS” on page 4-1.
EAM30224
CHECKING THE ENGINE OIL LEVEL
1. Start the engine and warm it up for ten min-
utes until the engine oil has reached a normal
temperature of 60

C (140

F), and then turn
the engine off.
2. Stand the vehicle upright on a level surface.
3. Start the engine, wait for ten seconds, turn
the engine off, and then wait a few minutes.
Manufacturer/model
NGK/LMAR8G
1
2
1
1
2
Spark plug gap
0.7–0.8 mm (0.028–0.031 in)
Spark plug
13 N·m (1.3 kgf·m, 9.6 lb·ft)
T
R
.
.