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How to adjust your carb and check jetting

Discussion in 'How-To' started by Gas Man, May 14, 2008.

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  1. Gas Man

    Gas Man Cool isn't cheap
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    This is a hot topic... posting the thread may help... here's a improved version of what we have told COUNTLESS people.

    To adjust the carb...

    Some educational reading by S&S

    S&S carb adjustments
    S&S Shorty Carburetor Adjustments

    S&S Carb Manual
    http://www.sscycle.com/files/7913/7..._g_series_shorty_carburetors_installation.pdf

    For my 2 cents...

    with the bike warm...
    (in=clockwise/out=counter)

    if your idle is low... turn it up a bit...

    now spin in the accel pump screw till it seats.

    now spin in your fuel/air mix screw till the motor sounds like it wants to die

    now spin it back out counting 1/4 turns. Do it slowly to give the motor/carb time to adjust. Do this till the motor sound like it wants to die on this end. Now you have counted those turns and you have say 2.5 turns. Spin it back in 1.25 turns. Or middle to almost dead on each end.

    Now adjust your idle to 1,000 rpms on the tach.

    Now spin the accell pump screw out 1.5 turns

    Now with a few quick stabs at the throttle see if the rpms come up fast like you would think or if it kinda hesitates then takes off. If it does hesitate then spin the accel pump out another 1/4 turn and repeat till you get what sounds good.

    If that don't fix the sneeze... you can spin out the accel pump a bit more... but anything over 2.5 turns MAY mean you need a larger intermiediate jet. This is a common debate.

    Then re-adjust your idle to about 1,000 RPMs. Too low and it may die. Too high and it will clunk into first gear.

    [​IMG]


    Now on the plugs... to test run the bike and see if the jets are good. This can also be done before you ever screw with your jets.

    Check or replace plugs.

    run the bike but keep the RPMS below 2500... then don't let it idle and kill the motor, check the plugs. That is to help check the int jet.

    Then take it out and run it hard... keep the RPMs up and romp on it... then on a striaght patch of road with the RPMs up high (over 3k, or even higher) kill the motor with the OFF switch. Pull the plugs and check. that is to test the main jet.

    The idea here is that your int jet runs from idle to about 2750. Then the main kicks in from there out. That's why we say your run mainly on your int jet. main is only for romps.

    Use this GUIDE to read your spark plugs. The basic idea is white is lean, black is rich. What you are aiming for is a nice cinnamon color to the grounding tip.

    To talk jetting...

    One of the most common problems is...if you are expierencing a cough at highway speed 75mph +/- RPMs at about 2750... cough thru the carb... go up on int. jet.

    To jet the carb... click these links for sniplets out of the how to
    (post #2, 7-8)

    http://www.bigdogbiker.com/forums/how/13-how-remove-your-carb.html#post58
    http://www.bigdogbiker.com/forums/how/13-how-remove-your-carb.html#post63

    Of coarse once you change the jets you will need to re-adjust the carb again.
     
    Big D Florida and francoblay1 like this.
  2. Raywood

    Raywood The Pirate
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    Making this a sticky!
    Thanks Gas Man.

    :cheers:
     
  3. Gas Man

    Gas Man Cool isn't cheap
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    Schweet!

    :2thumbs:
     
  4. f-okie

    f-okie AllGaveSome-SomeGaveAll

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    Chris, at the questioned smilie, what are you turning out 1.5 turns? The accel pump screw?
     
  5. Gas Man

    Gas Man Cool isn't cheap
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    Yes... and I don't recall why it has the smilie... start the accell pump dial in by starting at 1.5 turns out on the accell pump
     
  6. f-okie

    f-okie AllGaveSome-SomeGaveAll

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    Thanks Bro-that's what I thought, but just checkin:flag:
     
  7. BigDognSoCal

    BigDognSoCal Active Member

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    Does anyone know what the vent o the back of the carb is for? Its the one that is always covered up with a black vapor cap(zip tied)...Ive never seen one hooked up to any hose...Ive seen some carbs(I think older) that dont have it...In this picture its right of the cable pulley...If this leaks will it make the bike run erratic?

    [​IMG]
     
  8. f-okie

    f-okie AllGaveSome-SomeGaveAll

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    I guess this is my year for leaks--any idea why you'd leak fuel from the overflow on the bottom of the carb? The xXx carb has been on since Dec. and now it wants to leak every couple of days.:rant:
     
  9. slowrower

    slowrower 2007 Mastiff

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    I bet your float is sticking ... dam crappy dirty fuel these days!! read the Gasman's adding a fuel filter thread.
     
  10. mcgroom

    mcgroom Well-Known Member

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    You may think about pulling the carb first. Open, drain and clean it. Pull the jet and blow out with a bit of air.

    If it happens again after that, then go through the carb again, drain your tank to get any shit that is getting mixed in and pushed through your system.

    A filter will stop new shit from getting in, but not take care of anything already in there.

    Had to do this earlier this year on another bike and see it
     
  11. Gas Man

    Gas Man Cool isn't cheap
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    Gee mcgroom... sounds almost like my "good filter" thread.
     
  12. mcgroom

    mcgroom Well-Known Member

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    I have read and reread so many threads Chris that if it sounds like I am stealing your advice and offering it to someone else than at least you know that you are getting through to someone on here.

    If you study something you are interested in long enough it becomes ingrained into you.
     
  13. Gas Man

    Gas Man Cool isn't cheap
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    ingrained... yep... that is my life. I don't mind the passing on of common knowledge... we all have done that!
     
    francoblay1 likes this.
  14. gilbert7878

    gilbert7878 Member

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    Could this help my Popping on Decelartion?
     
  15. BubbleHead

    BubbleHead Big Dog Biker test account

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    Well stated Gas. After all isn't that principal one of the "misson Statements' of this fourm? :up:
     
  16. Gas Man

    Gas Man Cool isn't cheap
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    Agreed. If a guy learns something from my dumbass and then passes it on as their own knowledge. That is fine, cause they learned it and its their own at that point. ALL GOOD!! :2thumbs:
     
  17. Gas Man

    Gas Man Cool isn't cheap
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    I noticed one typo where I said to spin out the accell pump screw 1.5 turns... but I didn't say that I just said "it".... CORRECTED
     
  18. boost junkie

    boost junkie New Member

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    My Bike(s):
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    Does anyone have the sizes of the factory jets? I would like to know if my (used) bike has stock jets or not...
     
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