Yamaha VMAX 2009 Service Manual page 135

b. Check the vacuum pressure.
The difference in vacuum pres-
sure between the throttle bodies
should not exceed 1.33 kPa (10
mmHg).
If out of specification → Adjust the throttle
body synchronization.
L LLL L LLL L L LLL L
Adjusting the throttle body synchronization
1. Adjust:
• Throttle body synchronization
M MMM M MMM M M MMM M
a. Start the engine, warm it up for several min-
utes, and then let it run at the specified en-
gine idling speed.
Engine idling speed
950–1050 r/min
b. Using the front cylinder throttle body that has
the bypass air screw "1" with a white paint
mark as the standard, adjust the other throttle
bodies by turning their bypass air screws in or
out.
ECA2S31071
NOTICE
Do not turn the bypass air screw of the front
cylinder throttle body that is the standard.
Otherwise, the engine may run roughly at
idle and the throttle bodies may not operate
properly.
TIP
Do not use a rear cylinder throttle body as the
standard.
L LLL L L LLL L L LLL L
M MMM M M MMM M M MMM M
A
LLL
B
MMM
1
A. Left side
B. Right side
TIP
• After each step, rev the engine two or three
times, each time for less than a second, and
check the synchronization again.
• If a bypass air screw was removed, clean or re-
place the throttle bodies.
• The difference in vacuum pressure between
the throttle bodies should not exceed 1.33 kPa
(10 mmHg).
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2. Stop the engine and remove the measuring
equipment.
3. Allow the engine to cool, and then start the
engine and check that the engine speed does
not rise abnormally high.
4. Adjust:
• Throttle cable free play
Refer to "ADJUSTING THE THROTTLE CA-
BLE FREE PLAY" on page 3-9.
5. Install:
• Caps
3-8
1
L LLL L L LLL L L LLL L
Throttle cable free play
3.0–5.0 mm (0.12–0.20 in)
ENGINE
1
1
L LLL L LLL