Yamaha F40B - Synchronizing the Carburetor; Adjusting the Dashpot

FUEL
Fuel system
4-17 67C3K11
Synchronizing the carburetor
CAUTION:
Do not adjust the carburetors when they
are operating properly. Excessive adjust-
ment may cause poor engine perfor-
mance.
1. Remove the plugs 1, and then attach
the special service tool to the intake
manifold as shown.
2. Start the engine and warm it up for 10
minutes.
3. Attach the special service tool to spark
plug wire #1 3, and then check the
engine idle speed.
4. Check the vacuum pressure of all cylin-
ders.
5. Turn the synchronizing screws 4 in
direction a or b until the specified vac-
uum pressure is obtained.
NOTE:
• To increase the vacuum pressure, turn the
synchronizing screw in direction a.
• To decrease the vacuum pressure, turn the
synchronizing screw in direction b.
6. Check the engine idle speed. Repeat
steps 3–5 if out of specification.
Adjusting the dashpot
1. Start the engine and warm it up.
2. Attach the special service tool to spark
plug wire #1 1.
Vacuum gauge 2: 90890-03094
Digital tachometer: 90890-06760
S67C4034
1
2
S67C4035
3
Engine idle speed: 850 ± 50 r/min
Vacuum pressure:
42.6 kPa (319.5 mmHg, 12.6 inHg)
S67C4036
ab
4
S67C3033
1