Another wasted evening with the OS 91FX  
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    • All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> Another wasted evening with the OS 91FX
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    Another wasted evening with the OS 91FX - 7/23/2003 2:29:16 PM   
    nashtm



    Posts: 290
    Joined: 11/13/2002
    From: Port Elizabeth, SOUTH AFRICA
    Status: offline     		Hi

    I fitted a perry remote nv and its different motor !!!
    I am really enjoying it
    Tim

    (in reply to FLYBOY)
           Post #: 26

    Well Flyboy What is your Status? - 7/24/2003 8:20:33 PM   
    Crash King



    Posts: 159
    Joined: 12/18/2001
    From: Dallas, TX, USA
    Status: offline     		I also have a problematic 91 FX, So I am waiting to see how you fix yours. Please give us an update.

    I have tried the following
    1) Perry remote Needle valve
    2) Cline Regulator
    3) New Fule tank, lines fittings
    4) Du Bro 657 Anti Vibe mount

    The thing still gets bubbles in the Fuel System !
    Another wasted evening, heck I have 3 full days worth of time on this one.

    The only way I can get the bubbles out is by removing the fuel tank from the airframe. Then it works SWEET, Kind of hard to fly without a fuel tank in the aircraft though?

    The only thing left is a Tetra Bladder tank, and I find it hard to throw more money away on this. A 30.00 Fuel tank is hard to swallow on a 91FX But hey, With the time I have in this one it already is a $900.00-$1200.00 investment in a $ 200.00 engine.
    OS No MAS !

    < Message edited by Crash King -- Jul 24 2003 3:35PM >

    _____________________________

    Thanks,
    Crash

    (in reply to FLYBOY)
           Post #: 27

    Another wasted evening with the OS 91FX - 7/24/2003 11:59:46 PM   
    Throttle


     

    Posts: 196
    Joined: 6/4/2002
    From: Lufkin, TX, USA
    Status: offline     		Crash, It's sound like your fuel is foaming to me. At the present I fly only 2 cycle engines and I use Wildcat 2 & 4 Cycle total synthetic oil 18% and 10% Nitro fuel. There are three inexpensive fixes that would be worth a try. First place some foam between the fuel tank and the body of the airplane. Then I would add a Dubro Tank Filter. This is a large filter so you need a fuel tank with a large mouth opening Like Sullivan's. The filter also works as a clunk on you fuel line. If you still have problems try one to two shots (from spray bottle) of ArmorAll to the gallon of fuel. Sometime just one of these will fix the problem then again it might take all three.

    _____________________________

    Throttle

    (in reply to FLYBOY)
           Post #: 28

    Well maybe that would work - 7/25/2003 1:51:34 AM   
    Crash King



    Posts: 159
    Joined: 12/18/2001
    From: Dallas, TX, USA
    Status: offline     		But the fuel tank is suspended in Sig Latex Foam on 4 sides. I give the fuel a couple of quick squirts of Armor All.

    The Dubro Tank Filter is a new one, Hey If I can find it I will try it.

    I agree foaming is my problem, the fact that when the tank it is out of the airframe it runs fine supports this. This is why I was going to try the bladder tank. I also had someone suggest that I unpack the fuel tank as this may be why it foams.

    Again, sounds like a few more hours.

    Thanks for the reply

    _____________________________

    Thanks,
    Crash

    (in reply to FLYBOY)
           Post #: 29

    Another wasted evening with the OS 91FX - 7/25/2003 1:58:09 AM  1 votes
    FLYBOY



    Posts: 8692
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		I ordered the K&B remote needle. We will see how it works. Should be here next week. I thought about trying the armorall trick, but it isn't foaming from the tank, just from the needle to the engine. If the remote doesn't work, I am going to scrap the sucker and replace it. I have wasted way too much time on it. It flew good for a short while, but that was it.

    _____________________________

    Fly it till the wings come off.

    (in reply to FLYBOY)
           Post #: 30

    Another wasted evening with the OS 91FX - 7/25/2003 1:58:51 AM   
    Throttle


     

    Posts: 196
    Joined: 6/4/2002
    From: Lufkin, TX, USA
    Status: offline     		Yes Crash if you have the fuel tank packed to tight in the foam then that could be causing you problem. Some just pack it in the foam on three sides and have good results. Another thing that could be causing the foaming is an unbalanced prop. Be sure to make sure that it is balanced this can't be stressed enough. Go easy on the ArmorAll to much is a bad thing. If you shake a gallon of fuel it will foam like a head of beer. When you add the ArmorAll with one squirt shake the gallon of fuel and see if it still foams. If the foaming stops than all is fine. If it still foams give it one more squirt (that should do it for sure). I have never needed to go over two squirts.

    < Message edited by Throttle -- Jul 25 2003 3:11AM >

    _____________________________

    Throttle

    (in reply to FLYBOY)
           Post #: 31

    Ordered a remote carb valve - 7/25/2003 4:30:22 AM   
    Andre


     

    Posts: 30
    Joined: 10/13/2002
    From: Strathroy, ON, CANADA
    Status: offline     		Yea I ordered a K&B remote needle valve also ,I could not drill out the GMS carb large enough, one good thing I had no bubbles to be seen when I used the GMS carb leading to beleive the OS remote needle valve assembly is faulty. Andre

    (in reply to FLYBOY)
           Post #: 32

    Another wasted evening with the OS 91FX - 7/25/2003 6:39:58 AM   
    gwinhh-RCU


     

    Posts: 18
    Joined: 6/28/2003
    From: beaumont, VA,
    Status: offline     		I haven't read the whole thread, but "

    have you tried putting a piece of fuel tubing OVER the needle valve before you thread it in? Use a piece that will fit snugly over the needle valve and long enough to butt up against the think you turn in and out. Damn, that's dumb!!

    (1)---------------(2)MMMMMMMMMMMMM

    put tubing that will go from 1 to 2. it will eliminate leaks around the needle/needle housing.
    howell

    (in reply to FLYBOY)
           Post #: 33

    Another wasted evening with the OS 91FX - 7/25/2003 10:33:28 PM  1 votes
    FLYBOY



    Posts: 8692
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		WOW, Just got the K&B needle in the mail. That was fast! They have great cust service. I will put it on tonight and hopefully get time to try it in the morning. Hope it works.

    _____________________________

    Fly it till the wings come off.

    (in reply to FLYBOY)
           Post #: 34

    Another wasted evening with the OS 91FX - 7/26/2003 8:02:14 PM   
    sport10


     

    Posts: 715
    Joined: 12/31/2001
    From: Loxley, AL, USA
    Status: offline     		Has anyone considered the OS FSR 1.08 as a replacement to the 91 FX? It is abit expensive but looks to have about the same power to weight ratio.

    _____________________________

    Hind site is always 20/20.

    (in reply to FLYBOY)
           Post #: 35

    Another wasted evening with the OS 91FX - 7/26/2003 8:29:41 PM   
    lucien


     

    Posts: 72
    Joined: 6/29/2003
    From: Santa Fe, NM, USA
    Status: offline     		[QUOTE]Originally posted by sport10
    Has anyone considered the OS FSR 1.08 as a replacement to the 91 FX? It is abit expensive but looks to have about the same power to weight ratio. [/QUOTE]

    Seems to me another alternative is the .91 heli engine (the sx). Course, the problem there is the crankshaft looks barely long enough to fit a prop onto it.

    The 1.08 is a pretty big, heavy motor. I've seen it in a couple of guys' planes and it's a magnificent running motor, just kinda big to stick into a .60 size and probably even big for a .90 size plane too.

    And at its price, you could get a 1.60fx, giving you the option of a bigger plane, etc....

    Too bad you can't simply order the .91fx less carb and put on a better fuel system of your own...

    LS

    (in reply to FLYBOY)
           Post #: 36

    Another wasted evening with the OS 91FX - 7/27/2003 2:03:53 AM   
    dick Hanson



    Posts: 10176
    Joined: 12/12/2001
    From: slc, UT, USA
    Status: offline     		An earlier post from England by "sprink"- described exactly the problem I found on using the remote location -- that is, vibration.
    I setup a new engine on a bench and was able to easily see the problem - which showed it'self by ragged running .
    I removed the tubing from the assy and hand held the needle vale ass'y.
    the problem stopped - double checking - it was obvious that the bubbles originated at the remote needle.
    I can see where this could be a case by case thing .
    the needle fit -- a prop unbalance- a soft engine mount --any number of things

    (in reply to FLYBOY)
           Post #: 37

    Another wasted evening with the OS 91FX - 7/27/2003 3:03:22 AM   
    basmntdweller


     

    Posts: 1731
    Joined: 1/3/2002
    From: Indianapolis, IN, USA
    Status: offline     		A free fix, if vibration is the problem would be to cut the stock remote from the backplate and use goop or silicone to mount it to the firewall. If it solves the problem it hasn't cost a thing other than the time it took to cut it off and glue it on. If it doesn't solve the problem, still nothing lost. Also, I remove the little paper gaskets and put the needle assembly back together with Ultra Copper RVT being careful not to get any in the passages.
    I've been fortunate in that none of my rear mounted remotes have ever had a problem. I have a 91 on my U-can-do but it's with a perry pump. I have a 160FX and a 46 and a 50sx all with the remote needle. For those interested, My 91FX turns a Pro-zinger 15-6 at 9100 maxed out. I usually set it about 8800 on the ground.

    _____________________________

    Proud brother of the Profile persuasion!
    I got all cross****ed and turfed it, AGAIN!!

    (in reply to FLYBOY)
           Post #: 38

    Another wasted evening with the OS 91FX - 7/27/2003 8:54:43 PM   
    sport10


     

    Posts: 715
    Joined: 12/31/2001
    From: Loxley, AL, USA
    Status: offline     		I possibly found a carb with the same venturi dimensions as the one on the 91FX but it is a standard needle valve version. Just engines sells ASP carbs which just might very well fit the .91FX. The venturi size on the ASP carb is 9.5MM which is the same as the FX carb. Maybe someone would like to give them a call and discuss this with them. They carry OS engine and might be familiar with the problems with the engine and know if this carb will fit. If so this will get rid of the pesty remote needle valve which seems to be the cause of all these problems. The cost for the carb is 20 pounds.

    _____________________________

    Hind site is always 20/20.

    (in reply to FLYBOY)
           Post #: 39

    Another wasted evening with the OS 91FX - 7/28/2003 5:18:04 PM   
    SMALLFLY-



    Posts: 2151
    Joined: 12/9/2001
    From: Evansville, IN, USA
    Status: offline     		I have been running a os 91fx for over 2 years and it is a FANTASTIC motor, BUT when it was new the needle valve leaked air horribly. The new black o ring helped a little but a piece of large silicone tubing over the whole valve assembly (joint area especially) helped the most. There are still a few bubbles from time to time but it is a very reliable engine once you get the bubbles stopped

    (in reply to FLYBOY)
           Post #: 40

    Another wasted evening with the OS 91FX - 7/28/2003 7:11:10 PM   
    Sprink



    Posts: 2236
    Joined: 4/23/2003
    From: London, UNITED KINGDOM
    Status: offline     		Basmntdweller,

    what you describe is what I did to solve the problem, and it worked for me. Unfortunately, wasn't for free as I had already paid for a replacement backplate/needlevalve.

    Crash,

    I had a very annoying case of the bubbles a month or so back with a Saito 72. Tried everything to eliminate, but nothing worked. Eventually changed the clunk (that and tank were the only original things left) and that worked. Can only assume that the clunk was causing the fuel to foam as it was sucked in (vibration atain?).

    Sport10,

    When I had my problem, I sent it to Just Engines, but that was a couple of years ago so may have forgotten if no one else has contacted them.

    _____________________________

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

    (in reply to FLYBOY)
           Post #: 41

    Another wasted evening with the OS 91FX - 7/28/2003 7:14:55 PM