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Carb balancing on the cheap (pictures!)

Discussion in 'Mechanical & Technical' started by Skier, Mar 24, 2005.

  1. While it seems a lot of you guys have FI bikes, apparently injectors need to be balanced, too, so I guess this guide can apply. But for us poor carburated guys, one of these sure beats a $50 "econ" carb balancer or letting a shop do it once for $80.

    Gathering the parts
    For this project, you will need:
    * standard airline tubing (check the pet aisle of your local grocery store, or a pet store. My 20 feet of it was less than $4 American)
    * tape (masking or duct, I used masking since it was what I had)
    * ATF (automatic transmission fluid - just buy the cheapest stuff you can find)
    * something long you can tape the tubing to (I used some wood lying around the house, a yard/meterstick would work fine)

    Putting it all together
    You want to put the tubing so it makes a U around the long item, which I'll refer to as the yardstick from now on. Basically, you want to make the tubing have a good two or three feet of extra tubing from the top of the yardstick. This will let you run the tubing to the carb boots without moving the thing around too much. Tape the tubing into place.

    Now, stick one end of the tubing into the ATF and suck on the other end of the tubing. Try to get about 3/4 of the way up the yardstick on either side. Let the device sit for a bit afterwards for an hour or two to let the fluid settle. If you have too much in it, you can either blow out the excess or, if you haven't cut the tubing to length yet, make a loop at the bottom with the excess tubing.

    A picture is worth a thousand words, so here is an example one (not mine):
    http://www.screaming3d.com/pics/cb/synchtool.jpg

    If you have a vacuum operated petcock like my Radian and want to use your gas tank, cut up an extra section of about two feet or so of the airline tubing. This allows you to have a longer reach to the gas tank when you move it from its mounting location.

    Balancing the carbs
    Read this page for some background: http://www.dansmc.com/balancecarbs.htm . I put my bike up on the centerstand, pulled the tank off to the side so I could access the nipples on the carb boots and attached the device. Fire the bike up with the lines attached. Basically, if a carb is pulling more ATF into it than the other, you need to adjust them. I balanced carb one against two, then three, then four. Might not be the best way to do it, but it was sure better than it was. You might want to balance one to two, then three to four, then one to three (or four). This ensures the banks of carbs are balanced against each other.

    The screw you are looking for is this one:
    [​IMG]

    There are a total of three of them. One for carbs one/two, one for carbs three/four and one for the left carb bank (one and two) and the right bank (three and four).

    Here is a quickie diagram on how to set up the lines for balancing carbs one and two:
    [​IMG]

    And one and three:
    [​IMG]

    (Please forgive my lack of art skills, I'm a computer scientist for a reason. ;) )

    While this guide is for four cylinder bikes, a bike with two or three carbs should be quite similar. Any questions, please feel free to ask. And forgive any typos and whatnot, I'm exhausted from school.

    Many thanks to ronboskz650sr (from the totalmotorcycle forums) for giving me instruction on how to build and use one of these myself - saved some money on it, that's for sure! That's also his balancer pictured in the walk-through.
     
  2. jezterr

    jezterr Retired Admin

    what are carbs? :lol: :lol:
     

  3. Ahh young grasshopper back when.......
     
  4. Very Nice! Thanks Skier.
     
  5. Or, If you live near Kent Washington.

    I just purchased a brand new set of Gages from Bent Bike.

    You can show me how to use them.
     
  6. Jafar

    Jafar Retired Admin

    how often do you need to balance your carbs? and what happends if you don't?
     
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