Carb sync procedure for Carbtune

Discussion in 'General Vendor Display' started by dannymax, Jan 1, 2017.

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  1. Jan 1, 2017 #1

    dannymax

    dannymax

    dannymax

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    I know this is posted in several locations on the forum and....here's one more. :biglaugh:

    I will refer to the carbs by their factory designation, following is the orientation

    front

    #2 #4

    #1 #3

    rear

    The first photo is of the right side (sitting on the bike) of carbs #3 & #4 and shows 2 sync screws just above the mounting brace

    The second photo is of the left side (sitting on the bike) of carbs #1 & #2 and shows only 1 sync screw which points downward towards the mounting brace

    Be sure your bike is warmed up and shut off

    Place the Carbtune in an upright position above the gauges where you can see it from both sides of the bike (hang it on a long wire from the ceiling if possible)

    Remove the plastic intake manifold covers from both sides

    Remove the vacuum advance hose from #2 carb sync spigot and the rubber caps from #1, #3 & #4 carb sync spigots

    Attach the Carbtune hoses to sync spigots as follows....1st hose to #1 carb, 2nd hose to #2 carb and so on (makes it easier to keep track of which carb you're adjusting later on)

    Start the bike and adjust idle to 1100 rpm

    Adjusting the screws:

    Screwing them in drops the Carbtune rod, backing them out raises the rod

    The screw on the left side adjusts #1 carb only......(#2 carb is the master carb and has no sync screw, it is adjusted at the factory and the other carbs are sync'd to it)

    The 2 screws on the right side work as follows:
    -the rear screw adjusts #3 carb only
    -the front screw adjusts #3 & #4 simultaneously

    Procedure:

    Start on the left side by adjusting #1 carb to #2 carb
    Move to the right side and adjust #3 carb to #4 carb (using the rear screw)
    Adjust #3 & #4 carbs to #1 & #2 (using the front screw)

    Blip the throttle after each change

    The above process will involve moving from one side to the other as changes to one carb can minutely affect other carbs

    That's all there is to it....it probly sounds like a bunch of mumbo jumbo but becomes easy with a little practice.
     

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    rolling18 likes this.
  2. Jan 1, 2017 #2

    sdt354

    sdt354

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    Thanks Dan-o. It's important to a good performing Vmax. For those setting their A/F screws by the ear method, this must be done right first for good response from the A/F screws.
     
  3. Jan 1, 2017 #3

    SpecOps13

    SpecOps13

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    Great write up Dan-o
     
  4. Jan 1, 2017 #4

    dannymax

    dannymax

    dannymax

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    Thanks Dave.
     
  5. Jan 1, 2017 #5

    Tex85

    Tex85

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    Perfect write-up. To anyone who may hesitate, this is a super simple task to complete DIY (so easy, I can do it)!
     
  6. Jan 1, 2017 #6

    dannymax

    dannymax

    dannymax

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    Thanks Tex.
     
  7. Jan 2, 2017 #7

    tugla

    tugla

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    Sweet discription dannymax....
    Only thing I would add is
    Make sure to remove the screwdriver from the screw to view sync as it does chg just the pressure applied to the screw....
    I might have missed that in your discriptions ....just started my coffee
     
  8. Jan 2, 2017 #8

    dannymax

    dannymax

    dannymax

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    Absolutely right Rov.....they are very, VERY sensitive screws....miniscule adjustments only! :punk:
     
  9. Jan 2, 2017 #9

    Traumahawk

    Traumahawk

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    Great write up Danny.
     
  10. Jan 2, 2017 #10

    dannymax

    dannymax

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    Thanks Eric!
     
  11. Jan 3, 2017 #11

    tugla

    tugla

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    I might have learned that one over a piece of pie and ice cream down in ny state somewhere ...:punk:
     
  12. Jan 3, 2017 #12

    dannymax

    dannymax

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    Ya know....I think that might just be the case! :biglaugh:
     
  13. May 28, 2019 #13

    Demonsinmysemen

    Demonsinmysemen

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    Hey, dude. You've helped me out a lot in the past and I appreciate it it. Next step is the synchronisation of the carbs. I got a good deal from this post, although my base carb is basically reading zero unless I blip the throttle. I shot some carb cleaner on the boots and carb thinking there may be some sort of leak. No changes. Any recommendations?
     
  14. May 28, 2019 #14

    dannymax

    dannymax

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    Are they sync'd?
     
  15. Sep 9, 2019 #15

    rolling18

    rolling18

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    What numbers are you adjusting them too? whats the target #??
     
  16. Sep 10, 2019 #16

    Traumahawk

    Traumahawk

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    Its not really a set number, its more of having them all at the same number/level.
     
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  17. Sep 10, 2019 #17

    mabdcmb@yahoo.com

    mabdcmb@yahoo.com

    mabdcmb@yahoo.com

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    Mine typically ends up around 25 cm Hg but as Eric noted, all the same is what matters not a specific numba'
     
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