Yamaha F40BWHD - Synchronizing the Carburetor

CONTROL SYSTEM
3-9
E
CHK
ADJ
SYNCHRONIZING THE CARBURETOR
CAUTION:
Do not adjust the carburetor when it is
operating properly. Excess adjustment may
cause the engine poor performance.
1. C h e ck:
• Engine idling speed
Unstable → Adjust.
2. Adjust:
• Carburetor synchronization
Adjustment steps
(1) Remove all of the plugs .
(2) Install the adaptors and vacuum
gauge onto the intake manifold as
shown.
(3) Start the engine and allow it to warm
up for several minutes.
(4) Install the tachometer onto the spark
plug lead of cylinder #1.
(5) Adjust the engine speed to 900 r/min by
turning the throttle stop screw on
carburetor #3 in direction or .
(6) Measure the vacuum pressure of carbu-
retor #3.
1
3
1
2
Vacuum gauge set
YU-08030/90890-03159
Tachometer
YU-08036-A/90890-06760
D
DD
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on
n n
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Engine speed increases.
D
DD
Di
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ec
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Engine speed decreases.
1
2
3
4
a b
a
b