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Thread: KF II, gasoline containing ethanol

  1. #1

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    Default KF II, gasoline containing ethanol

    Hi guys,
    I am considdering buying an 1991 KF II with fiberglass gasoline tanks. Can I use the normal super MOGAS containing up to 10% ethanol in my KF?
    BR
    sidenius

  2. #2
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    Default Re: KF II, gasoline containing ethanol

    I personally wouldn't use alcohol laced gasoline. I have had server problem with the alcohol. The engine will do fine with the alcohol, but the tanks do not like alcohol. The alcohol will strip epoxy & mold release out of the tank. The engine's carburetors will have problems with the epoxy & mold release. It can result in a very bad trip. I have a SLSA Kitfox, the tanks are suppose to be able to take unleaded, if you search my older post you will see where, I got to slosh my tanks, replace all fuel lines, and rebuild my carbs. I would never use the unleaded with alcohol. I don't know what percentage of alcohol they use in auto fuel gasohol in Texas 10%, or 20%, but it's too much, because it yellows and cracks my sight gauges. I would imagine it has something to do with the winter versus summer blends of fuel, no telling what different companies put in the fuel.

    I've tried using unleaded without alcohol aka mogas, but it yellows my sight gauges quite badly, I quit using it because I don't like changing my sight gauges every year. besides alcohol.
    Last edited by Paul Z; 06-17-2015 at 10:17 AM.
    Paul Zimmermann
    LSRM-A
    Garland, Texas

  3. #3
    Senior Member jiott's Avatar
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    Default Re: KF II, gasoline containing ethanol

    Definitely do not used mogas with alcohol in those older tanks.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  4. #4
    Senior Member HighWing's Avatar
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    Default Re: KF II, gasoline containing ethanol

    There is definitely a generationally influenced tint to the previous comments.

    First, mold release is painted on the mold to allow the finished product to be removed without damaging the mold. The shape of the tanks - surface finish inside and out - definitely indicate the mold was a female mold. The smooth outer surface and the glass fiber texture on the inner surface visible through the filler neck is the clue. The mold surface is always the smooth surface. There is no mold release inside the tank. If there is gunk requiring sloshing, it is most likely uncured resin as most resins are oxygen inhibited meaning they will not thoroughly cure if exposed to air. This will occur on the lay-up - exposed surface - side, not on the mold release side. This phenomenon is limited historically to the Ethanol resistant tanks currently produced by Kitfox Aircraft. It was an issue that never came into the discussion with the early tanks.

    Second, it was while flying my first Model IV - 2003 - that the powers that be decided to mess with the gas - MTBE to Ethanol. I continued to fly using the Ethanol laced fuel. I did have one issue that came up with extremely small leaks at the top of the tank inboard of the filler neck, but resloshed with Kreem - yes, that much maligned Kreem - and it solved the problem. I continued flying with 10% ethanol until my oil pressure problem and emergency landing destroyed that airplane in 2007. During these four years, I averaged about 100 hours per year.

    Of the 4-5 thousand Kitfoxes out there, the vast majority have the early tank formulation and construction. I seriously doubt Kitfox has sold even close to 1000 pair of the newly formulated resin tanks. There are tons of the early Kitfoxes flying using the original tanks with the typically available auto fuel.

    This is not necessarily an endorsement one way or the other, but is primarily intended to shine a little historical light on the fuel tank issue.
    Lowell Fitt
    Goodyear, AZ


    My You Tube Channel

  5. #5
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    Default Re: KF II, gasoline containing ethanol

    I called John when I encountered this problem. He said it was probably mold release that was causing my problem, and not the epoxy. (John never got to see the carburetors.) He told me because they were using an epoxy to build tanks that was (supposed to be) unaffected by alcohol. I do concur with your comment that it looks like the inside should have no mold release, because of the tank design and the required mold pull would put the mold release on the outside of the tank, not the inside. That is why I said mold release and epoxy, it has to be one or the other. I guess I should have said, mold release or epoxy. The tanks were supposed to have been sloshed at the factor. If the epoxy was suppose to be alcohol resistant, and if there there was no mold release, than what would be the culprit?

    In looking at the sludge in my carburetors, it was kind of brownish, like the epoxy. I have no way of testing the material, but Dean from Lockwood & I both looked at the carburetors during the Rotax training class at Blue Ridge Community College. We both guessed it was the epoxy that was the culprit. I sent my carbs to Lockwood to be rebuilt on Thursday, and I had them back by the next Monday, very good Customer Service.

    When I had my problem, I had my throttle stuck at cruise speed, I came in to land with no ability to chop the throttle. I went around the patch once, then I set up for landing on base, killed the engine, and did a dead stick landing. Other than the gasohol, I am not 100% sure of what caused the problem, but I'm 100% sure I am not willing to risk another problem. After my issue I'm 100% sure I'm not willing to use Gasohol again. Better safe than dead.
    Last edited by Paul Z; 06-17-2015 at 01:20 PM.
    Paul Zimmermann
    LSRM-A
    Garland, Texas

  6. #6
    Senior Member Av8r_Sed's Avatar
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    Default Re: KF II, gasoline containing ethanol

    I have 1991 vintage tanks in my III. It is my belief that the resin used in these tanks is not compatible with Ethanol. I can purchase Ethanol free 91 RON fuel less than an hour's drive from me so I choose to ferry fuel by auto, about 40 US gallons per trip. I haven't had any fuel related issues over the past four years.
    -- Paul S
    Model III SN910
    582 IVO Med

  7. #7

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    Default Re: KF II, gasoline containing ethanol

    Definitely not! A friend had problems after using 10% ethanol fuel He hadn't even done 100hrs on the plane. He had to re-slosh his fuel tanks.
    I run unleaded MOGAS (91,95 or 98). I test the fuel for ethanol every once in a while to make sure the local supplier has not added any ethanol to the mixture.
    Here in Australia it is actually hard to find fuel that is E10 (10% ethanol) allegedly.... All other MOGAS does not have ethanol (or at least it is not advertised)

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