Yamaha YZ125X 2023, Owner'S Manual

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ENGINE
3-6
NOTICE
ECA13330
Before removing the spark plug, blow away
any dirt accumulated in the spark plug well
with compressed air to prevent it from falling
into the cylinder.
3. Check:
• Spark plug type
Incorrect

Change.
4. Check:
•
Electrode “1”
Damage/wear

Replace the spark plug.
•
Insulator “2”
Abnormal color

Replace the spark plug.
Normal color is medium-to-light tan.
5. Clean:
•
Spark plug
(with a spark plug cleaner or wire brush)
6. Measure:
• Spark plug gap “a”
(with a wire thickness gauge)
Out of specification

Regap.
7. Install:
•
Spark plug
TIP
Before installing the spark plug, clean the spark
plug and gasket surface.
8. Connect:
•
Spark plug cap
EAM30539
CHECKING THE TRANSMISSION OIL LEVEL
1. Start the engine, warm it up for several min-
utes and wait for five minutes.
2. Place the machine on a level place and hold
it up on upright position by placing the main-
tenance stand under the engine.
3. Check:
•
Transmission oil level
a. Remove the oil check bolt “1”.
b. Inspect the oil level.
TIP
Be sure the machine is positioned straight up
when inspecting the oil level.
WARNING
EWA21090
Never attempt to remove the oil check bolt
just after high speed operation. The heated
oil could spout out, causing danger. Wait un-
til the oil cools down.
Oil flows out

Oil level is correct.
Oil does not flow out

Oil level is low.
Add transmission oil until oil flows out.
c. Inspect the gasket (oil check bolt), replace
if damaged.
d. Tighten the oil check bolt.
EAM30540
CHANGING THE TRANSMISSION OIL
1. Start the engine and warm it up for several
minutes and wait for five minute.
2. Place the machine on a level place and hold
it on upright position by placing the mainte-
nance stand under the engine.
3. Place a suitable container under the engine.
Manufacturer/model
NGK/BR9EVX
Spark plug gap
0.6–0.7 mm (0.024–0.028 in)
Spark plug
20 N·m (2.0 kgf·m, 15 lb·ft)
G088879
T
R
.
.
Type
Motor oil SAE 10W-40 type SG or
higher
Quantity (disassembled)
0.76 L (0.80 US qt, 0.67 Imp.qt)
Quantity
0.70 L (0.74 US qt, 0.62 Imp.qt)
Oil check bolt
10 N·m (1.0 kgf·m, 7.4 lb·ft)
T
R
.
.