Yamaha F40BED, Service Manual, Page: 86 / 537

CHK
ADJ
3-5
CONTROL SYSTEM
E
ADJUSTING THE ENGINE IDLING
SPEED
NOTE:
The engine should be warmed up for the
adjustment.
Correct adjustment cannot be obtained
when the engine is cold.
1. Measure:
• Engine idling speed
Out of specification
→
Adjust.
Measuring steps
(1) Start the engine and allow it to warm
up for a few minutes.
(2) Install the tachometer onto the spark
plug lead of cylinder #1.
2. Adjust:
• Engine idling speed
Adjustment steps
(1) Turn the throttle stop screw in direc-
tion or until the specified engine
idling speed is obtained.
(2) Check the engine idling stability. If
engine idling is unstable, adjust the
pilot screw and synchronize the carbu-
retors.
NOTE:
Rev the engine two or three times and keep
it idling for at least 15 seconds after adjust-
ment to check the engine’s stability.
Engine idling speed
850±50 r/min
Tachometer
YU-08036-A/90890-06760
1
b
a
Direction
Engine idling speed
increases.
Direction
Engine idling speed
decreases.
1
a b
a
b