Yamaha YZ125 2019 Owner's Service Manual page 67

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 suitable
stand under the engine.
3. Place a suitable container under the engine.
4. Remove:
• Oil drain bolt "1"
• Oil filler cap "2"
Drain the transmission oil.
5. Install:
• Aluminum washer
• Oil drain bolt "1"
Oil drain bolt:
20 Nm (2.0 m•kg, 14 ft•lb)
6. Fill:
• Transmission oil
Recommended brand: YAMALUBE
Recommended engine oil type
SAE10W-40
Recommended engine oil grade
API service SG type or higher
JASO standard MA
Oil capacity (periodic oil change):
0.66 L (0.58 Imp qt, 0.70 US qt)
7. Check:
• Oil leakage
8. Check:
• Transmission oil level
9. Install:
• Oil filler cap "2"
ADJUSTING THE PILOT AIR SCREW
1. Adjust:
• Pilot air screw "1"
Adjustment steps:
a. Screw in the pilot air screw until it is lightly
seated.
b. Back out by the specified number of turns.
Pilot air screw:
2-1/4 turns out
ADJUSTING THE ENGINE IDLING SPEED
1. Start the engine and thoroughly warm it up.
2. Adjust:
• Engine idling speed
Adjustment steps:
a. Loosen the locknut "1".
b. Turn the throttle stop screw "2" until the en-
gine runs at the lowest possible speed.
c. Tighten the locknut.
To increase idle speed → Turn the throttle
stop screw "2" in.
To decrease idle speed → Turn the throttle
stop screw "2" out.
3-12
ENGINE