SYNCHRONIZING THE THROTTLE BODIES
© cvvmax December 2013
Before synchronizing the throttle bodies, check the following items:
    • Valve clearance
    • Spark plugs
    • Air filter element
    • Throttle body joints
    • Fuel hoses
    • Exhaust system
    • Canister purge hoses (for California)
    • Breather hoses

1. Stand the vehicle on a level surface.
Place the vehicle on a suitable stand.

2. Check:
    • Engine idling speed

    a. Start the engine, warm it up for several minutes, and then let it run at the
        specified engine idling speed.
Engine idling speed
950-1050 r/min

Out of specification -> Clean or replace.

3. Remove:
    • Air filter case

4. Disconnect:
    • Intake air pressure sensor hose " 1 "
    • Cap "2"
5. Install:
    • Hose " 1 " (Parts No.: 5JW-24311-00)
    • 3-way joint "2" (Parts No.: 90413-05014)
    • Vacuum gauge hose #1 "3"
    • Vacuum gauge hose #2 "4"
    • Intake air pressure sensor hose "5"
    • Vacuum gauge "6"
    • Digital tachometer
Vacuum gauge
90890-03094

Vacuummate
YU-44456

Digital tachometer
90890-06760
YU-39951-B
6. Install:
    • Air filter case

7. Adjust:
    • Throttle body synchronization

    a. Measure the vacuum pressure of the front cylinder throttle body and rear
        cylinder throttle body.

    b. Using the throttle body with the lowest vacuum pressure as the standard, turn
        the air screw " 1 " of the other throttle body to adjust its vacuum pressure.

    c. If the vacuum pressure of the throttle body with the lower pressure is out of
        specification, adjust it to specification first, and then synchronize the throttle
        bodies.
A. Front cylinder throttle body
B. Rear cylinder throttle body
    • After each step, rev the engine two or three times, each time for less than a
       second, and check the synchronization again.
    • If the air screw was removed, turn the screw in fully, and then turn it out 1-1/4
       turns. Then, synchronize the throttle bodies.
Do not use the throttle valve adjusting screws to adjust the throttle body synchronization.
Intake vacuum
34.7-40.0 kPa (260-300 mmHg,10.2-11.8 inHg)
The difference in vacuum pressure between two throttle bodies should not exceed 1.33 kPa (10 mmHg).

8. Measure:
    • Engine idling speed

    If out of specification -> Adjust.

    Make sure that the vacuum pressure is within specification.

9. Stop the engine and remove the measuring equipment.

10.Connect:
    • Intake air pressure sensor hose
    • Cap

11.Install:
    • Air filter case

12.Adjust:
    • Throttle grip free play
Throttle grip free play
4.0-6.0 mm (0.16-0.24 in)
© 2013-15 cvvmax. No animals, HDs or Ducatis were harmed in the making of this site.