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Thread: Air-Fuel Ratio at corner exit

  1. #1

    Default Air-Fuel Ratio at corner exit

    Anyone have any air/fuel ratio data they would like to share? I'm seeing that as I get back on the thottle in a corner I get a rich ratio (~10), but then after 5 seconds it comes up to the 12.5 range. I don't know if this is something I can tune, or if it's just what happens in a corner. Gear changes on the straights don't show this, so I'm assuming it has something to do with the corner.

  2. #2
    Join Date
    Jan 2010
    Location
    Houston-ish
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    932

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    Carb or fuel injection?

    10:1 isn't necessarily bad for the engine, but it doesn't make as much power as it could. No idea how to tune that out if it's a carb (smaller accelerator pump volume maybe?), but you can adjust your tip-in or throttle-up values on a fuel injected system for a little less enrichment.
    Houston Region
    STU Nissan 240SX
    EProd RX7

  3. #3
    Join Date
    Oct 2002
    Location
    Concord, NH 03301
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    700

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    Are you flat at that time? If not, who cares. If you are only putting in as much throttle as the tires can handle, it doesn't matter that you're not making full power. You watch the tach on a lot of high powered bikes, they are way down in the RPM range, but since they'd be spinning the rear wheel w/ more throttle, it is faster to stay in the higher gear as you have fewer changes down the straight.

    I don't discount that it is odd. However I would want to see on the straight how long it takes to equalize when you go from partial throttle to flat, squeezing it down, not making the change quickly. When you do an upshift, you go from flat, lift, flat very quickly. The motor has been off the throttle for a bit at the turn and is probably at neutral throttle, or low amounts of accel prior to you going flat. This difference may be why you don't see the problem on upshifts.

  4. #4
    Join Date
    Oct 2002
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    Concord, NH 03301
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    700

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    Good tequila, double post.
    Last edited by MMiskoe; 06-09-2014 at 08:11 PM. Reason: double post

  5. #5
    Join Date
    Feb 2001
    Location
    Trussville, Alabama, USA
    Posts
    1,087

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    If carb, there will be a vent tube on top for the float bowl. Add a length of hose to this, or better still, three circles of hose terminating vertically. What is happening is fuel is exiting the vent tube into the venturi.
    Chuck Baader
    White EP BMW M-Techniq
    I may grow older, but I refuse to grow up!

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