A Guide to Marauder Carburetor Synchronization

Thanks to Bob Arnold #7947 for this article

What is a carburetor Sync?

On engines that have two or more carburetors it is necessary for all carbs to do the same amount of work, otherwise one cylinder does the majority of the work and you end up with a rough running engine.
In its simplest form, Synchronizing the carburetors is adjusting the butterflies in all of the carbs to open an close at the same rate, thereby ensuring that all cylinders are doing there share of work.

What is adjusted to sync the carburetors?

  1. Engine RPM
  2. Air/fuel mix to 1-3/4 turns out
  3. Carb sync adjustment cable

What tools are needed to sync the carburetors on a Suzuki Marauder?

  1. Tachometer
  2. Two vacuum gauges with restrictors
  3. One 8 and 10 mm open end wrench
  4. One small flat blade screw driver

Suzuki Marauder carburetor synchronization instructions

  1. Make sure the enrichment valve operates freely
  2. Hook up your tachometer
  3. Hook up your vacuum gauges with restrictors to front and rear carburetors
  4. Set air/fuel mix screws at 1-3/4 turns out (California Marauders)
  5. Remove the throttle cables at the handlebar
  6. Disconnect the throttle cable at the splitter on the left hand side of the front air cleaner
  7. Adjust both pull cables to be the same length
  8. Start engine and warm up
  9. Set the idle to 800 RPM
  10. Adjust the rear carburetor sync cable for a close vacuum reading between both gauges (within 1 inch of vacuum)
    (Note: When facing the rear carb, turning the rear adjuster clockwise will increase the vacuum on the rear carb and decrease the vacuum on the front)
    Re-check the idle RPM and adjust to 800 RPM if necessary
    (You will need to adjust the RPM several times while you sync the carbs)
  11. Remove vacuum gauges and install sync gauge.
  12. Adjust the rear carburetor sync cable for a balance between front and rear carbs.
    Note: Little adjustment should be required at this point. If your vacuum reading was within 1 inch of each other, then this step may not be required and is only for a visual verification of sync
  13. Remove sync gauge and install vacuum gauges on both carbs
  14. Check and adjust the idle speed to 800 RPM, then adjust the air/fuel mix screws on both carbs for the highest balanced vacuumi reading (You will only need to adjust the idle/air screw about i 1/8-1/4 turn) Re-check the idle RPM and adjust if necessary
  15. Readjust if necessary the throttle pull cables to be the same length
  16. Reconnect the throttle pull cables that were disconnected in step 4
  17. Re-assemble the throttle cables at the handlebar
  18. Adjust the pull and return throttle cables at the handlebar
  19. Increase engine speed to 2500 rpm
  20. Check and re-sync if necessary the rear sync adjuster cable for balance between front and rear carbs
  21. Put the bike back together and take it for a test run.