Yamaha F40BED, Service Manual, Page: 88 / 537

CHK
ADJ
3-6
CONTROL SYSTEM
E
ADJUSTING THE PILOT SCREW
CAUTION:
Do not adjust the carburetor when it is
operating properly. Excess adjustment may
cause the engine poor performance.
1. Check:
• Engine idling speed
Unstable
→
Adjust.
2. Adjust:
• Pilot screws
NOTE:
Depending on the model, each pilot screw
is covered with blind plugs.
Adjustment steps
(1) Turn in all of the pilot screws until
they are lightly seated.
(2) Turn out the pilot screws the specified
number of turns.
(3) Start the engine and warm it up to
check the engine for stability.
(4) If the engine speed is unstable, follow
the steps as below.
(5) Install the tachometer onto the spark
plug lead of cylinder #1.
(6) Turn the pilot screws in until the engine
idling speed is down approximately 50
r/min, and then return the screws 5/8
turns.
1
SAV only
Pilot screw setting
2±1/2 turns out
Tachometer
YU-08036-A/90890-06760
1