Yamaha YZ250F(S) Owner's Service Manual page 194

VALVE CLEARANCE INSPECTION AND ADJUSTMENT
2
c
ENGINE IDLING SPEED ADJUSTMENT/
ENGINE IDLING SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it
up.
2. Adjust:
Engine idling speed
G
Adjustment steps:
Adjust the pilot screw.
G
Refer to "PILOT SCREW ADJUSTMENT"
section.
Turn the throttle stop screw 1 until the
G
specified engine idling speed.
NOTE:
Using a digital engine tachometer for idle
speed adjustment, detect the engine idling
speed by bringing the sensing element c of
the engine tachometer close to the ignition
coil 2.
To increase idle speed → Turn the throt-
tle stop screw 1 in a.
To decrease idle speed → Turn the throt-
tle stop screw 1 out b.
Engine idling speed:
1,900 ~ 2,100 r/min
VALVE CLEARANCE INSPECTION AND
ADJUSTMENT
NOTE:
The valve clearance should be adjusted
G
when the engine is cool to the touch.
The piston must be at Top Dead Center
G
(T.D.C.) on compression stroke to check or
adjust the valve clearance.
1. Remove:
Seat
G
Fuel tank
G
Refer to "SEAT, FUEL TANK AND
SIDE COVERS" section in the CHAP-
TER 4.
2. Drain:
Coolant
G
Refer to "COOLANT REPLACEMENT"
section.
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INSP
ADJ