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  1. #1

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    OS max 52 surpass 4 stroke is this true

    I bought an OS max 52 surpass 4-stroke for my .40 size spitfire I am building, I got a good price, 50.00 It has a prop on it,, I turned it over by hand and noticed there was not much compression at all, on the compression stroke,I hear the valvetrain moving, so I believe it is all working,, The seller told me that the engine will not really have compression until it has fuel in it?? is this true,, I am new to these engines, I bought it he seemed like an honest enough old timer,
    Thanks fellas

    I also have to mount it inverted, I was told I have to use an onboard glow driver to help prevent flooding and dying at low throttle?

  2. #2

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    RE: OS max 52 surpass 4 stroke is this true

    Fuel and warming up will help compression. Also check the valve settings.

    Tom

  3. #3

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    RE: OS max 52 surpass 4 stroke is this true

    Sometimes, if they sat in storage for a while, they will only get good compression after running for a minute or so.
    Pe, (www.mvvs.nl), MVVS, MOKImotor, RCexl, MTW, Xoar, Mejzlik.
    Blessing in ignorance? There is sanctuary in analysis.

  4. #4
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    RE: OS max 52 surpass 4 stroke is this true

    Also, if the throttle is all the way closed when you're turning it over...that can make the compression feel soft...
    < Wrongway Feldman's Kreider-Reisner KR-21...(on Gilligan's Island)

  5. #5

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    RE: OS max 52 surpass 4 stroke is this true

    I have the same engine from new that had the same issue when i turned it over from been laid up for a couple of years, a stuck valve was the cause.

  6. #6

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    RE: OS max 52 surpass 4 stroke is this true

    You need to make sure the valves aren't gummed up but more than likely it just needs to be run some and as to the onboard glow driver if an engine is adjusted correctly and the fuel tank is in the correct position with the carb there is no need for an onboard glow driver all it will do is add weight to your spit and you will want to eliminate all the weight you can if you are putting a .52 on a .40 sized model I normally try to put at least a .70 four stroke on a .40 size plane but it just depends on the total weight of the model. Just my .02
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  7. #7

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    RE: OS max 52 surpass 4 stroke is this true

    I had a 5.5 kilo Spit using an OS90 4-stroke (not surpass)
    The engine was mounted inverted, and I had a Micro switch operated on board single NiCd cell for glow, active below 1/3rd throttle, dead on throttle cut.
    I could idle the engine at about 1400 rpm. When I cut glow support, it would die. Very convenient to set up, and weight certainly was no problem at all. The (Sterling kit) Spit would fly just like the real thing. Nothing Jackrabbit, but steady.
    Pe, (www.mvvs.nl), MVVS, MOKImotor, RCexl, MTW, Xoar, Mejzlik.
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  8. #8

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    RE: OS max 52 surpass 4 stroke is this true


    ORIGINAL: pe reivers

    I had a 5.5 kilo Spit using an OS90 4-stroke (not surpass)
    The engine was mounted inverted, and I had a Micro switch operated on board single NiCd cell for glow, active below 1/3rd throttle, dead on throttle cut.
    I could idle the engine at about 1400 rpm. When I cut glow support, it would die. Very convenient to set up, and weight certainly was no problem at all. The (Sterling kit) Spit would fly just like the real thing. Nothing Jackrabbit, but steady.
    I had the same set-up on my pilot pitts, a 3amp sub c battery and micro switch. Although it would idle fine, it was quite 'lumpy' and the onboard glow smoothed it out to super sweet !
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  9. #9

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    RE: OS max 52 surpass 4 stroke is this true

    That was then and this is now. Get a Switch Glo which plugs directly to your receiver. No extra battery. Works great in a big plane where you have a big battery anyway. Not good if you use a AA pack in a small plane.

  10. #10

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    RE: OS max 52 surpass 4 stroke is this true

    They lose compression when sitting for a while, especially if they have been flipped dry a lot. A small amount of glow fuel, or after run oil shot into it will boost compression before you can run it if you want to feel compression in it.
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