Yamaha XG250, Service Manual

Page: 57 / 278

ENGINE
3-6
Refer to “REPLACING THE AIR FILTER EL-
EMENT” on page 3-12.
●
Carburetor
Refer to “CARBURETOR” on page 6-3.
EAS20590
CHECKING THE EXHAUST GAS
(When the air induction system is operating)
1. Stand the vehicle on a level surface.
NOTE:
●
Place the vehicle on a suitable stand.
●
Make sure the vehicle is upright.
●
Measure the exhaust gas at idle when the air
induction system is operating.
2. Install:
●
Temperature probe tester “1”
(onto the engine oil drain bolt)
●
Digital tachometer
3. Start the engine and warm it up until the
specified oil temperature is reached.
4. Measure:
●
Engine idling speed
Out of specification
→
Adjust.
Refer to “ADJUSTING THE ENGINE IDLING
SPEED” on page 3-6.
5. Install:
●
CO/HC tester “1”
●
Sampling prove “2”
NOTE:
●
Since it is necessary to insert the sampling
probe 600 mm into the exhaust pipe, be sure
to use a heat-resistant rubber tube as shown
in the illustration.
●
Be sure to set the heat-resistant rubber tube
so that exhaust gas does not leak out.
6. Measure:
●
CO density
Out of specification
→
Check the air induc-
tion system.
Refer to “AIR INDUCTION SYSTEM” on
page 6-9.
7. After checking the air induction system, re-
check the exhaust gas at idle when the air in-
duction system is operating.
EAS20610
ADJUSTING THE ENGINE IDLING SPEED
NOTE:
Prior to adjusting the engine idling speed, the
carburetor synchronization should be adjusted
properly, the air filter element should be clean,
and the engine should have adequate compres-
sion.
Pocket tester
90890-03132
Digital tachometer
90890-06760
Oil temperature
95.0
–
105.0
°
C (203.00
–
221.00
°
F)
Engine idling speed
1300 – 1500 r/min
1
CO%
0.5
–
1.5 %
1
2
600mm