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  1. #1

    2015 FX SVHO - "ribbon delete" (flame arrestor) removal and Fuel / Air (AFR) question

    Haven't really modified a ski in a number of years, but used to all the time back in the day.

    Back then, Carbs were the thing, so fuel / air ratios were generally easily adjustable.

    My question is, if you remove the stock flame arrestor element (I guess what people are calling ribbon delete), and replace with a K&N or whatever, does the ECU compute the added air coming in and adjust fuel accordingly (adding more), or does the AFR change because now you have more air, but the ECU doesn't know you changed anything so still supplies the same amount of fuel as before, so now you are running leaner than you used to be?

    Also, does somebody make a "spacer" to take up space in the air inlet near the intake manifold when you remove the stock arrestor? Seems like air flow would be turbulent if you didn't put something in there.

    Any other mods come to mind that wouldn't drastically degrade fuel economy at sane cruising speeds (say +/- 5K)?

    Thanks for any insight.


  2. #2
    Quote Originally Posted by iamjcl View Post
    Haven't really modified a ski in a number of years, but used to all the time back in the day.

    Back then, Carbs were the thing, so fuel / air ratios were generally easily adjustable.

    My question is, if you remove the stock flame arrestor element (I guess what people are calling ribbon delete), and replace with a K&N or whatever, does the ECU compute the added air coming in and adjust fuel accordingly (adding more), or does the AFR change because now you have more air, but the ECU doesn't know you changed anything so still supplies the same amount of fuel as before, so now you are running leaner than you used to be?

    Also, does somebody make a "spacer" to take up space in the air inlet near the intake manifold when you remove the stock arrestor? Seems like air flow would be turbulent if you didn't put something in there.

    Any other mods come to mind that wouldn't drastically degrade fuel economy at sane cruising speeds (say +/- 5K)?

    Thanks for any insight.
    The ECU adjusts for the "ribbon delete" being gone. My 2015 FX SVHO did just fine with the added air

  3. #3
    The Rooster's Avatar
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    Riva makes a "sleeve" that fits in the lip created when you remove the ribbon. Jerry sells them in the online store !!!

  4. #4
    04gtxsc's Avatar
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    What sort of change did you see when you removed the ribbon?

  5. #5
    The Rooster's Avatar
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    Quote Originally Posted by 04gtxsc View Post
    What sort of change did you see when you removed the ribbon?
    John you need to update your avatar w/ your new ski !!! A little quicker acceleration & slightly better fuel mileage.

  6. #6
    Quote Originally Posted by Sam SHO View Post
    Quote Originally Posted by iamjcl View Post
    Haven't really modified a ski in a number of years, but used to all the time back in the day.

    Back then, Carbs were the thing, so fuel / air ratios were generally easily adjustable.

    My question is, if you remove the stock flame arrestor element (I guess what people are calling ribbon delete), and replace with a K&N or whatever, does the ECU compute the added air coming in and adjust fuel accordingly (adding more), or does the AFR change because now you have more air, but the ECU doesn't know you changed anything so still supplies the same amount of fuel as before, so now you are running leaner than you used to be?

    Also, does somebody make a "spacer" to take up space in the air inlet near the intake manifold when you remove the stock arrestor? Seems like air flow would be turbulent if you didn't put something in there.

    Any other mods come to mind that wouldn't drastically degrade fuel economy at sane cruising speeds (say +/- 5K)?

    Thanks for any insight.
    The ECU adjusts for the "ribbon delete" being gone. My 2015 FX SVHO did just fine with the added air

    I realize though that it could still run "just fine" a little leaner than it used to run. That used to be a big part of tuning skis (I guess still is - getting it to that point where if you go any leaner you might sieze the pistons).

    Do you know for sure that the ECU is mapping more fuel now that you have removed the FA element?

    The Rooster notes above that he sees better fuel economy after removing it - sounds like no extra fuel is being mapped (leaner)?

    Thanks!

  7. #7
    Quote Originally Posted by The Rooster View Post
    Riva makes a "sleeve" that fits in the lip created when you remove the ribbon. Jerry sells them in the online store !!!
    Thanks!

  8. #8
    lets race.... mikeFZR's Avatar
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    AFRs with the ribbon delete and other stage 1 mods is perfectly safe. Mods in my sig ran the following AFRs:

    Idle: 10.8
    2000: 12.1
    2500:13.0-13.2
    3000: 13.9
    4000: 12.8-13.1
    5000: 12.4-12.6
    6000: 12.3-12.5
    7000: 12.0
    7730 (wot): 11.8-12.1 (mostly 11.9)

    Edit: just realized you are talking about a SVHO. My numbers are for a SHO.

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