Adjusting The Engine Idle Speed - Yamaha EK25BMH Service Manual

CHK
CONTROL SYSTEM
ADJ

ADJUSTING THE ENGINE IDLE SPEED

NOTE:
• The engine should be warmed up for the
adjustment. Correct 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
1,300 ± 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 digi-
tal 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 (
2
:Kerosene) until they are lightly seated.
(2) Turn out the pilot screws by specified
number of turns.
Pilot screw turn-out
Gasoline carburetor: : : :
1 - 1/2 ± 1/2
Kerosene carburetor:
1/2 + 2
1/2 - 1/2
3-15
E
1
onto
1
1
:Gasoline,