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  1. #1
    Canadian Beaver Inspector jkindt's Avatar
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    Efficiency of F/A's

    How much of a difference is there in changing your F/As. I have noticed that a lot of the bolt on upgrades seem to include aftermarket F/As. Is there something inherently inefficient about the stock F/A? Does it have something to do with having one intake for three carbs and the difference in airflow from one end to the other? I see most of the aftermarket F/As are either three individual parts, one for each carb, or a single piece with air intake from all sides of the unit rather than from one end. Also, do the aftermarket units include a type of velocity stack to improve air speed through the carbs, or is this an additional part? I do not know much about the F/As on these motors. What is the limitations of the stock blue fuji F/A?


  2. #2
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    Some F/A's have a sort of velocity style form to them,in the OP's it's a cone built into the top. Mainly aftermarket ones allow more flow then stock. That is why you normally need to increase the fuel using the needles,or even stepping up a jet size.

  3. #3
    Canadian Beaver Inspector jkindt's Avatar
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    Would this be something I need to consider with my SLeeper project?

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Keddano View Post
    ...Mainly aftermarket ones allow more flow then stock...
    Does that apply primarily to the Fuji Flame Arrestors, and not so much for the domestic FA?
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  5. #5
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    K, That style ones are better then the plastic box style. You could measure the Square inches of filter area,and I bet they are real close to the OP's. From what I've been told those are very good. The fuji box styles have the opening that's fist size and also a very restritive perforated metal plate to prevent the flame backfire.

    Yes,I would say any style of aftermarket is a upgrade and needed for better flowing with power adding upgrades.

  6. #6
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    f/a's

    the stock domestic flowed all the air we needed when i was flowing the stock 40's,sleeper 40's and the 42's.the blue fuji version like the domestic moves enough air as well.the 650 one with the opening at one end was restrictive,installing just the later fuji version is an upgrade but will require carb adjustments

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by TxPro1200 View Post
    ..the blue Fuji version [that looks like] like the domestic FA moves enough air as well.

    the 650 one with the opening at one end was restrictive, installing just the later Fuji version is an upgrade but will require carb adjustments
    Good info

    So the better flowing Polaris OEM flame arrestor for the Fuji engines is the 2530019 version of the Fuji air intake filter (Flame Arrestor), found on these models;

    1996-1997 SLT780
    1996-1997 SL780
    1997-2000 Pro 785

    The cover 5432234-157 COVER, INTAKE, BON.BLUE(EC78 )
    and the 5630597 BASE, INTAKE,(EC78 )
    with the 2530019 filter was OEM on 1996-1997 SL780 and SLT780


    The Pro 785 had the 5432443-070 CVR, INTAKE, AIRBOX, BLK and 5630658 BASE, AIR INTAKE with the 2530019 filter


  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by TxPro1200 View Post
    ...installing just the later Fuji version is an upgrade but will require carb adjustments
    How much of an adjustment?

    High speed screw only, or jetting changes?

  9. #9
    Canadian Beaver Inspector jkindt's Avatar
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    Now look what I started! Everyone's gonna be buying up these higher flowing F/A's. I better not get left out of the good deals!

  10. #10
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    Quote Originally Posted by K447 View Post
    How much of an adjustment?

    High speed screw only, or jetting changes?
    I would say just adjusting the high would get you there. Based on OP's owner saying you can run them with just adjusting. But the same set-up from Polaris provided new HS jets.

    Trying to make sense of the # in the service manual and the jets changed about every year on the 780's.

    So I'd have to say as with any fuel/carb/or exhaust mod. AFTER PERFORMING A UPGRADE,ALWAYS CHECK AND WATCH YOUR PLUG CHOPS AND PISTON WASH TILL YOU ARE SURE YOUR NOT RUNNING LEAN AND THE SKI IS DIALED IN PROPERLY.

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