Another wasted evening with the OS 91FX  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
More Resources on the
O.S. .91 Ringed
  • 5 Active Classified Ad(s)
  • See User Ratings
  • Suggest Compatible Equip.
  • Check for Retailers
  • Discussions on this Product


    • All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> Another wasted evening with the OS 91FX
    Page: [1] 2 3 4 5 6 7   next >   >>  

    Login
    Message << Older Topic   Newer Topic >>
    Another wasted evening with the OS 91FX - 7/18/2003 7:25:07 PM  1 votes
    FLYBOY



    Posts: 8691
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		I have been having the bubble problem on all my OS engines with rear needles. I replaced the O ring in the needle and took it out again. This has been going on all summer. There was no change, accept the bubbles are a bit less, and the engine quits sooner than it did before. Figure that one out.

    I have been flying for over 27 years and have never had an engine run this bad. My smaller FX engines do the same thing. The needle is very prone to changing the mix and if you screw it out farther, it doesn't seem to get richer, it just quits. There is like 3 clicks where it runs well for a few minutes, but then just dies.

    My last try will be to find a carb that will fit it with the needle in it. Does anyone know of one that will fit the 91FX???

    I tried the carb from the .61 fs and it doesn't work.

    If that doesn't work, I am about to crush it and buy a super tigre or TT.

    If OS continues to put the needle in the back, I know two large clubs that will never buy them again. Just about everyone in both has tried to make this thing work.

    I emailed the Hobbico OS rep and he didn't even bother to respond. All of the other reps there have been great. If I owned Hobbico, I would fire this guy. I can't believe he didn't even take the time to answer with a stab at a solution. I know there are a lot of people having problems with these engines because you read it on here all the time.

    Sorry for the rant. If anyone has any ideas I would love to hear them. It ran good for about 2 tanks and I liked it when it worked. Would hate to drop back to a 61 or 75 but that is what I am going to have to do.

    < Message edited by RCadmin -- 11/2/2003 6:21:13 PM >

    _____________________________

    Fly it till the wings come off.
           Post #: 1

    Another wasted evening with the OS 91FX - 7/18/2003 7:46:07 PM   
    rcflyertim



    Posts: 71
    Joined: 8/1/2002
    From: Bridgewater, VA, USA
    Status: offline     		I don't fly rear needle engines for many reasons. You just gave me another reason not too!! In all fairness, I guess this is a very acceptable way to do it and that many hours of R&D have gone into the process. It has to be a real good idea for safety sake, to keep the fingers futher away from the prop. Lots of luck and sorry that I do not have a great solution to your problem.
    I would send it back and ask them to replace it.

    (in reply to FLYBOY)
           Post #: 2

    Another wasted evening with the OS 91FX - 7/18/2003 7:52:00 PM  1 votes
    FLYBOY



    Posts: 8691
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		Would like to, but have had it for about a year. I thought about sending it to them anyway and seeing what they charge to test it and see what they can do, but with 3 of them having the same problems, I figure I am ready to cut my losses and use a different brand. I have a new Webra Speed 61 in the box that will fly the plane well, or an old 61 SF that runs great. Wish I wouldn't have sold my Super Tigre .75. Will probably order another one. They run so well. I have an NIB 91 FX yet. Was going to put the pair in a Super Duelist I have. Not even a consideration now. Have to get a pair of ST .75s instead. Bummer.

    As you said, Lots of time spent in R and D. Too bad they didn't spend a little more and make something that works.

    < Message edited by FLYBOY-RCU -- Jul 18 2003 3:38PM >

    _____________________________

    Fly it till the wings come off.

    (in reply to FLYBOY)
           Post #: 3

    Another wasted evening with the OS 91FX - 7/18/2003 8:27:12 PM   
    lucien


     

    Posts: 72
    Joined: 6/29/2003
    From: Santa Fe, NM, USA
    Status: offline     		[QUOTE]Originally posted by FLYBOY
    Would like to, but have had it for about a year. I thought about sending it to them anyway and seeing what they charge to test it and see what they can do, but with 3 of them having the same problems, I figure I am ready to cut my losses and use a different brand. I have a new Webra Speed 61 in the box that will fly the plane well, or an old 61 SF that runs great. Wish I wouldn't have sold my Super Tigre .75. Will probably order another one. They run so well. I have an NIB 91 FX yet. Was going to put the pair in a Super Duelist I have. Not even a consideration now. Have to get a pair of ST .75s instead. Bummer.

    As you said, Lots of time spent in R and D. Too bad they didn't spend a little more and make something that works.

    I have also heard about an oversized O ring tower sells in packs of 2 for $15. Bad enough that they can't make it work, but then they rape you on a 50 cent O ring. Thats adding insult to injury.     [/QUOTE]

    I've been following this for a while myself. I used to have a .61fx; it was mounted on a great planes ugly stick. It was the most flawlessly running motor I've ever owned and it never gave any problems either on the plane or on the bench.

    I'm about to purchase a 1.60fx for another project.

    My personal suspicion is a fuel flow problem (what else could it be) caused probably by excessive heating of the needle valve unit. This looks particularly troublesome on the .91fx, being as how, just eyballing a picture of the motor, the needle is _right_ there behind the head (and that motor probably runs hot anyway due to the large displacement/small crankcase size) and attached directly to the backplate of the motor by a surely very good heat-conducting flange.

    The .61fx probably doesn't have the problem to that great of a degree since it's a smaller motor (puts out less heat) and the needle valve doesn't appear to be right behind the head. That, combined with the completely open-air installation on my stick, is probably why I didn't have trouble with mine.

    On the 1.60fx, the needle appears to just be attached with that bolt on bracket which won't conduct too much heat to the valve.

    Anyway, it shouldn't be too hard to debug this problem, since overheating/leaning/quitting ain't rocket science to figure out. It can only be one of two things: not enough fuel or not enough air-cooling (or both).

    Has anyone tried sawing the needle off the backplate and mounting it somewhere away from heat? I think I heard of someone doing that in another thread and that fixed it.

    LS

    (in reply to FLYBOY)
           Post #: 4

    Another wasted evening with the OS 91FX - 7/18/2003 8:34:32 PM  1 votes
    FLYBOY



    Posts: 8691
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		I thought about it, but haven't done it. Still a possibility but I would hate to do it.

    _____________________________

    Fly it till the wings come off.

    (in reply to FLYBOY)
           Post #: 5

    Another wasted evening with the OS 91FX - 7/18/2003 8:57:07 PM   
    pikebishop


     

    Posts: 402
    Joined: 12/21/2002
    From: md.
    Status: offline     		you might try getting a K&B remote needle valve and mounting it on the firewall.

    (in reply to FLYBOY)
           Post #: 6

    Remote needles - 7/18/2003 9:56:34 PM   
    Hobbsy



    Posts: 10677
    Joined: 12/2/2001
    From: Colonial Beach, VA, USA
    Status: offline     		Fox also makes a remote needle that has a great seal in it and I'm not the first to say that here.

    _____________________________

    "I have gone faster backwards, upside down and on fire than most people have gone at all" Don Garlits

    (in reply to FLYBOY)
           Post #: 7

    OS.91FX - 7/18/2003 9:57:19 PM   
    DarZeelon



    Posts: 7083
    Joined: 4/9/2003
    From: Rosh-Ha'Ayin, ISRAEL
    Status: online     		It looks like OS made a boo-boo with this engine.
    It is incomplete, half-baked. Hoses and nipples need replacement by altenative larger sizes. It doesn't run out of the box.

    It isn't representative of OS's mostly quality products.

    _____________________________

    Dar Zeelon - ISRAEL - ddzeelon@gmail.com
    MVVS - Jett - Nelson - Bolly - Mejzlik

    (in reply to FLYBOY)
           Post #: 8

    Another wasted evening with the OS 91FX - 7/18/2003 10:27:58 PM   
    Ed Cregger



    Posts: 7736
    Joined: 1/31/2002
    From: Ringgold, GA, USA
    Status: offline     		Just go to the Conley website, get their phone number, call them up and tell them you need a Perry carb for your engine. Problem solved forever.

    (in reply to FLYBOY)
           Post #: 9

    Another wasted evening with the OS 91FX - 7/18/2003 10:57:24 PM   
    rcflyertim



    Posts: 71
    Joined: 8/1/2002
    From: Bridgewater, VA, USA
    Status: offline     		Flyboy,
    Even though your engine is 2 yrs old. I would still send it back for repair. They will still be able to look at it and make any repairs necessary. The only way they are going to make any changes is if people like you tell them it is a bad design!

    < Message edited by rcflyertim -- Jul 20 2003 3:23AM >

    (in reply to FLYBOY)
           Post #: 10

    Another wasted evening with the OS 91FX - 7/18/2003 11:10:14 PM   
    Crash90



    Posts: 2315
    Joined: 10/5/2002
    From: Cressona, PA, USA
    Status: offline     		I have owned 3 os 61fx engines. 2 of them ran perfect right out of the box. They both had the factory muffler. The 3rd one had a pitts style muffler and I had experienced the same problems that you are. I plugged up one of the pipes and everything was fine. Possibly you have a problem with tank pressure. What kind of muffler are you using?

    (in reply to FLYBOY)
           Post #: 11

    FX Remote Needle - 7/19/2003 12:04:29 AM   
    Ed_Moorman



    Posts: 3683
    Joined: 1/5/2002
    From: Shalimar, FL, USA
    Status: offline     		I have one that I hated until I got a K&B remote needle valve assembly. It really works. I hack sawed the OS remote needle off my engine and threw it in the trash.

    Go to this URL http://www.modelengine.com/parts/61.htm, it's the K&B site. The part number is 92-9255, $15.95.

    _____________________________

    Ed Moorman, AMA 553, KD4QBM, Revver Bro #156
    R/C Report Magazine, Fun Aerobatics Column

    (in reply to FLYBOY)
           Post #: 12

    Not heat - 7/19/2003 12:54:45 AM   
    Sprink



    Posts: 2236
    Joined: 4/23/2003
    From: London, UNITED KINGDOM
    Status: offline     		As far as I am concerned, while the engine does generate a lot of heat, this is not the cause of the problem. My own experience, supported on other threads is that if you have the bubble problem it is there from the start.

    The issue seems to be vibration. My theory is that the engine is causing the needle tip to vibrate enough to cause the fuel to foam as it passes.

    Mine now runs fine. I cut off the needle valve, and it is now mounted behind the engine on the firewall. The engine itself is on soft mounts. This isolates the needle valve from the vibration, and I no longer have the problem.

    I have never heard of this problem on any other OS, my 61FX, 32 SX and 25 LA have all run very well.

    _____________________________

    "If it doesn't break, it is probably too heavy"

    (in reply to FLYBOY)
           Post #: 13

    Another wasted evening with the OS 91FX - 7/19/2003 8:18:03 AM  1 votes
    FLYBOY



    Posts: 8691
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		Ok, here is what I have all done. I re-did the fuel system, no help, I put a new O ring on, no help, New plug, twice, no help.

    I put an OS .61 SF on and it runs great so it isn't the fuel system.

    I really like the idea of a K & B remote needle. I will order one and see what it does. I suspect that will help a ton. I think the problem is in the remote mounted to the back of the engine. Don't know if it is heat or vibration. I will get he K & B needle and let you know how it works. I would order a carb, but if I have to spend another $60 to make it work, I would rather sell it and buy a Super Tigre. I definately won't buy another OS with a rear needle again. This is bull.

    The new Stik flew really nice with the .61. Needs the added power though because I built it for 3D with the 91 in mind and it is heavier than a normal stik. Sweet bird though.

    _____________________________

    Fly it till the wings come off.

    (in reply to FLYBOY)
           Post #: 14

    FLYBOY.... - 7/19/2003 11:42:51 AM   
    Flyboy Dave



    Posts: 13448
    Joined: 3/20/2002
    From: San Bernardino County, CA, USA
    Status: offline     		....what size is the mounting flange on the carb...?

    I don't own a remote needle carb....they suck....

    ....sometimes literally....

    _____________________________

    An engineer says.... "That won''t work".
    A mechanic says..."Oh yeah, watch this".
    "Old Age, and Treachery will overcome youth and skill".
    Revver Bro #4.

    (in reply to FLYBOY)
           Post #: 15

    Another wasted evening wit