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  1. #26
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    RE: 95 AX run in problems.

    If your Sundowner 50 is a model originally intended for a .50-size two-stroke engine, then the .95 FX would be considered grossly large. That would encourage air being introduced into the fuel by the engine's vibrations. This air will lean the mixture and cause the engine to die.

    Put the engine on a very solid test fixture and see how it runs. If it runs "all day", then there are no problems with the engine, iteself, but in the engine/airframe/fuel system combination.
    Bill Baxter, Manager Hobby Services/Futaba Service/North America
    3002 N. Apollo Dr. Ste. 1 Champaign, IL 61822 USA
    Service Phone: 217 398-0007
    Email: hobbyservices@hobbico.com

  2. #27

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    RE: 95 AX run in problems.

    Hello,....I have the answer to your headaches my friend !! !

    I had this issue with this particular engine along with other OS95AX users and it has baffled the best of the best of pros with these OS engines. THE ANSWER IS THE GLOW PLUG. They don't like anything but the F PLUG. I know that some oldtimers refuse to accept that an OS engine does not run well on a #8 plug. But this one does not. After several months of agony and many tests. I changed to an F PLUG and wala !!! Engine runs great. Have been runing on an F plug for about 3 months now straight and absolutely no cut offs, no dead sticks, no nothing. WORKSGREAT!! After you make sure your fuel tubing is not too short as that may also cause you some problems, change your plug to an F and problem solved my friend. Let us know how it goes !!

    Alex

  3. #28

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    RE: 95 AX run in problems.

    I'm having all the same problems as above with the OS 95 AX - I think it is time for OS to become more involved in solutions for this engine as its marketability is definitely being questioned. Does anyone remember the fiasco of the 91 FX when it first appeared? "O" rings were wrong and the heating of the needle valve really messed up settings.

    I buy OS products for the quality that I expect and pay a premium price for that privilege. I also have damaged some nice planes using this engine and I'm not a beginner. You'd think by now that the recommended prop sizes would reflect reality etc!

    Bax- thanks for your input but I'm afraid you are in a difficult position here.

  4. #29

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    RE: 95 AX run in problems.

    I purchased an OS 95 AX about four months ago. I installed it in a Wot4 XL using its own exhaust, own plug and mounting it on its side. It ran fine on the ground, but after 3 to 4 minutes of flight cut out on a regular basis.
    After seeing this thread I then used a type F plug which eliminated the problem. I have recently put the engine into a Seagull Zlin 50, again side mounted but this time with a Just Engines Pitts silencer.
    Its reverted back to the old problem. I am still using the type F plug, I have even tried the bar type. I have checked the plumbing and asked several different flyers to set up the needles as they would normally do but it still stops at around 3 -4 minutes and with about half throttle.
    Any ideas?

  5. #30
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    RE: 95 AX run in problems.

    Your symptom is that of a too-lean engine. Very likely, your exhaust system does not provide enough pressure to the fuel system to give you good fuel flow. As a result, the engine gradually overheats and then quits. You may need to reduce the exhaust outlet area of the muffler to increase the pressure sent to the fuel tank.
    Bill Baxter, Manager Hobby Services/Futaba Service/North America
    3002 N. Apollo Dr. Ste. 1 Champaign, IL 61822 USA
    Service Phone: 217 398-0007
    Email: hobbyservices@hobbico.com

  6. #31

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    RE: 95 AX run in problems.

    Thanks Bax for your reply. I have recently spoken to "Just Engines" company within the UK and they have said the same thing. I am hoping to fly this weekend with one of the two exhaust outlets blocked up to see what that does.
    Thanks again for your reply.

  7. #32

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    RE: 95 AX run in problems.

    I HAVE THEFIXTOTHEOS 95AX PROBLEM
    I have 2OS 95AX that I bought in 2009 and they ran great till summer 2011. The engine would be getting this mid RPM burbling noise and would quit without warning. I could get the engine to run great on the ground and then it would quit in the air. I pushed my troubleshooting and during summer 2012 I got 10 dead sticks. A true intermittant problem that made me sweet. All successfull landing with talent and luck.
    I could go on and on to tell you my troubleshooting but lots has been said on this thread. What fixed my OS 95AX problems just before I was about to give up was to add a gasket under the head from my second OS 95 AX. YES! add a shim or gasket, what ever you want to call it and watch that engine come back to life. It is possible that just replacingthe head gasket with a new would be OK,but this is working great for the past 6 flights.


  8. #33
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    RE: 95 AX run in problems.

    Adding a head gasket will work if the engine's overcompressed for the fuel being used. More nitro means you should lower compression. Less nitro means you should raise compression. Lowering compression can help a lot in some cases.
    Bill Baxter, Manager Hobby Services/Futaba Service/North America
    3002 N. Apollo Dr. Ste. 1 Champaign, IL 61822 USA
    Service Phone: 217 398-0007
    Email: hobbyservices@hobbico.com


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