Adjusting The Engine Idle Speed - Yamaha 25BMH Service Manual

CHK
CONTROL SYSTEM
ADJ

ADJUSTING THE ENGINE IDLE SPEED

NOTE:
• The engine should be warmed up for
the adjustment.
cannot be obtained when the engine is
cold.
• Make sure that the pilot screw adjust-
ment is normal before implementing
idling stop screw adjustment.
1. Measure:
• Engine idle speed
Out of specification → Adjust.
Engine idle speed
1,100 ± 50 r/min
CAUTION:
Install the engine in the test tank to check
the engine idle speed.
Measuring steps
(1) Start the engine and allow it to warm
up for a few minutes.
(2) Install the digital tachometer
the spark plug lead of cylinder #1.
(3) Press the position key "C" on the digital
tachometer.
Digital Tachometer........................
90890-06760
2. Adjust:
• Carburetor pilot screw
CAUTION:
Do not adjust the carburetor when it is
operating properly. Excessive adjustment
may cause the engine poor performance.
Adjustment steps
(1) Turn in the pilot screw
lightly seated.
(2) Turn out the pilot screws by specified
number of turns.
Pilot screw turn-out
1 - 1/4 ± 3/4
3-16
E
Correct adjustment
1
onto
1
1
until they are