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Thread: D47U Pony Motor running backwards?

  1. #1
    Join Date
    Jul 2019
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    FLETCHER, OK 73541
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    Confused D47U Pony Motor running backwards?

    Just rebuilt my pony motor and started it a few times just for 15 or 20 seconds at a time. I took a video of that and just noticed that it was running backwards on the last go. I did start it with a rope as I don't have the starter back on yet. It sounds good and starts easy and I watched the video several times to make sure my eyes weren't crossed....has this happened to anyone else? I forgot to add the pony is still on the bench not mounted yet. Thank you in advance!

  2. #2
    Join Date
    Nov 2006
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    McBEE, SC
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    Default

    I've never roped one backwards, so I won't say its impossible, but the odds that the mag would fire correctly and the cam would work correctly as well seems very slim to me. Have you looked at the arrow cast into the flywheel?
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  3. #3
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    Jul 2019
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    FLETCHER, OK 73541
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    Ok, I am blind. Thanks for your reply sir. I slowed the video down and it was running clockwise and kicking back on compression after it died. I guess the higher rpm gave it that look of reverse rotation. Thank God!
    Last edited by Spazcat; 08-14-2019 at 07:25 PM.

  4. #4
    Join Date
    Jan 2017
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    388

    Default Video

    Video has a bad habit of turning the rotation backwards!
    View aircraft propellers, or fans, in your case the flywheel, they turn backwards in many video.

    Very difficult to get a 4 stroke engine to run backwards - 2 stroke can be a bit different.

    cts

  5. #5
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    Jul 2019
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    FLETCHER, OK 73541
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    Yep, fooled me...LOL! First time I have rebuilt any engine and had the jitters..Thanks!

  6. #6
    Join Date
    Nov 2006
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    Pittsford NY
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    Default

    Very good question though, and you were right to ask it.
    Cheers,
    Neil.

  7. #7
    Join Date
    May 2012
    Location
    Gowrie Junction, Darling Downs, Queensland
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    I had a similar experience once while viewing the rear display on my digital camera while looking out the window while flying in a turbo-prop aircraft. The propeller appeared to be almost stationary giving the illusion there was an engine issue!

  8. #8
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    Jul 2019
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    I slowed the video down enough to see the exact second that the flywheel "appeared" to reverse much like a hubcap on a car at a certain speed. Well, a little embarrassing but glad to know. Appreciate all!

  9. #9
    Join Date
    Sep 2017
    Location
    Petaluma, CA, Cats at Penngrove , CA
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    74

    Default optocal delusion!

    Seen it many times on cars in video, seems the wheels are turning backwards but the car is going forwards, glad it was the video image not the motor.

  10. #10
    Join Date
    Nov 2006
    Location
    Victoria Australia
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    You blokes all forgotten the old western movies where the wagon wheels all went bacwards. Know a guy that gets on here that spent some time trying to start a D2 winding the rope on the wrong way. Didn't work or seem to do it any harm. cheers WF

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