RE: os 91 in U-CAN-DO  
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    • All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> RE: os 91 in U-CAN-DO
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    RE: os 91 in U-CAN-DO - 9/23/2003 4:45:44 AM   
    rajul



    Posts: 6379
    Joined: 6/18/2002
    From: Missouri City, TX, USA
    Status: offline     		Thanks kwizard, I'll do that.

    (in reply to kwizard)
           Post #: 101

    RE: os 91 in U-CAN-DO - 9/23/2003 3:17:42 PM   
    2thelmt



    Posts: 102
    Joined: 12/28/2001
    From: Acton, ON, CANADA
    Status: offline     		I tried the fuel tubing over the needle-valve but it didn't work for me. I ended up cutting the needle-valve off of the back plate and re-mounting it to the fire wall. I have had no dead-sticks at all! The only thing I notice is a lean out after throttling down from full-this seems to stabilize after about 5 seconds. I run a BCM pitts ( .90 size) with no problem, and a 13.5 X 8 Graupner which I highly recommend.
    Ian

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           Post #: 102

    RE: Another wasted evening with the OS 91FX - 9/23/2003 3:46:52 PM   
    FLYBOY



    Posts: 8692
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		Well, I got the 91 back from Hobbico. They replaced the piston, ring, cyl liner, 2 fuel inlets and the plug screw. A friend sent his in with the exact same problems as mine. We got them back about the same time and he had the exact same parts changed. Both engines ran exactly the same when they came back. Neither one showed any improvement. It is really frusterating. The thing heats up and quits about 3 minutes into flight. The problem has to be in the needle system, but they didn't change anything there. I have a note into the pres of that division, but haven't heard from him yet. Will let you know how it turns out. Right now I am really not happy with OS on this change. The tech I talked to on the phone was not really helpfull. Most of the others I have talked to have been great. I really hope they help me out more with this. So far they have been pretty good to work with. I guess I am lucky. Out of over 25 OS engines I have, this is the only one I have ever had trouble with.

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           Post #: 103

    RE: Another wasted evening with the OS 91FX - 9/23/2003 8:21:17 PM   
    raptor5900



    Posts: 822
    Joined: 3/29/2003
    From: orchard park, NY, USA
    Status: offline     		hi guys i'm also having this problem but with a perry pump on it it seems to bubble before the needle and i've checked all the lines.......i noticed that with the tuned pipe on it it runs extreamly hot is this normal?


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           Post #: 104

    RE: Another wasted evening with the OS 91FX - 9/23/2003 8:30:44 PM   
    jaka


     

    Posts: 4627
    Joined: 12/11/2001
    From: Upplands Vasby, SWEDEN
    Status: offline     		Hi!
    Only if you run it lean........

    (in reply to raptor5900)
           Post #: 105

    RE: os 91 in U-CAN-DO - 9/23/2003 9:06:35 PM   
    FLYBOY



    Posts: 8692
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		Man, I was running rich as heck. It still leaned in the air.

    Sounds like Hobbico is going to help me out on it. Sounds like they have had this problem with quite a few. Man, I wish I could have made it work. Would have been a sweet engine. They need to put the needle back in the carb where it belongs. That would solve the problem so fast.

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           Post #: 106

    RE: os 91 in U-CAN-DO - 9/23/2003 9:22:37 PM   
    Strykaas



    Posts: 4121
    Joined: 3/21/2003
    From: Paris, FRANCE
    Status: offline     		I definitely cannot understand why OS engines are going that way

    I assume if they came back to the SF series, quite a few would be happy ... Nope, this is not supposed to happen .

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           Post #: 107

    RE: Another wasted evening with the OS 91FX - 9/26/2003 4:16:18 AM   
    PilotLight



    Posts: 855
    Joined: 8/15/2003
    From: Benton Harbor, MI, USA
    Status: offline     		I've finally got the engine running good, but it was on a engine test stand. I received a new rear cover plate. The old needle valve was broke off the engine so I let it hang by some blue medium fuel line. The engine ran OK, but the important thing was there was NO air in the fuel line. Next we changed the glow plug from a Fox with an idle bar to a 0 S #8. (more improvement) Finally, we noticed the fuel tank had a lot of fuel splashing inside so we decided to balance the prop. We found the prop was perfectly balanced on a magnetically suspended balancer, so we installed the propeller so that when the piston was at top dead center the propeller was horizontal not vertical. This produced a lot less vibration and the engine ran perfectly.

    To sumarize:

    * New fuel tubing between needle valve and carb
    * remove needle vavle from rear of engine (eliminate vibration)
    * run OS plugs
    * mount prop horizontally to piston top dead center (this made big difference)

    If anyone else has success with any of these changes, please post technique and results.

    (in reply to FLYBOY)
           Post #: 108

    RE: os 91 in U-CAN-DO - 9/28/2003 5:56:03 AM   
    Gone to a Higher Plane



    Posts: 264
    Joined: 10/25/2002
    From: Austin, TX, USA
    Status: offline     		Post removed by moderator!

    < Message edited by hobbsy -- 9/28/2003 2:33:05 PM >

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           Post #: 109

    RE: Another wasted evening with the OS 91FX - 9/28/2003 7:59:45 PM   
    Strykaas



    Posts: 4121
    Joined: 3/21/2003
    From: Paris, FRANCE
    Status: offline     		What the hell was he saying ?

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           Post #: 110

    RE: Another wasted evening with the OS 91FX - 9/28/2003 10:39:27 PM   
    nedyob


     

    Posts: 1240
    Joined: 2/5/2002
    From: NORTHWOOD, IA, USA
    Status: offline     		Had something to do with OS and where the sun don't shine.
    NEDYOB

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           Post #: 111

    RE: Another wasted evening with the OS 91FX - 9/28/2003 11:10:49 PM   
    beto9



    Posts: 111
    Joined: 8/22/2002
    From: Montreal - Quebec, QC, CANADA
    Status: offline     		I am using (correction, was...) the OS .50 SX, which uses the same remote needle valve as the .91 FX.
    Same problems as described above, the most puzzling aspect is that the bubles generate between the needle valve and the carburetor. So, the logical conclusion is that either the o-ring in the needle valve or the white gaskets in both sides of the nipple are at fault. Added a little lenght of fuelt tubing to the needle to seal the entrance to the housing. Not solved.
    Changed the gaskets, same problem... the engine hesitates, surges and slows down, and then runs OK. The hesitations and surges are usually after idling down, in flying terms when you are at the end of your taxing and about to take off. Very, very unsettling.
    I have ordered new o-rings, not received yet but I suspect the problem will still be there.
    There are two other spots where the bubbles may get in: the intake nipple before the needle and the intake nipple in the carburetor, both fitted with the same white gaskets (smaller, of course) than the nipple.
    I made the test of running with an external tank and the results were inconclusive. Besides, is VERY evident that the bubbles form between the needle valve and the carburetor, not before (tank to needle valve), as many ground runs have proven to me.
    Now, is OS taking any action on this. I'll repeat this problem in the manufacturers forum and I'll not want a wishy-washy answer. From there to the Japan site of OS is just a mouse click away.
    Albert

    (in reply to FLYBOY)
           Post #: 112

    RE: Another wasted evening with the OS 91FX - 9/28/2003 11:42:07 PM   
    Strykaas



    Posts: 4121
    Joined: 3/21/2003
    From: Paris, FRANCE
    Status: offline     		OS engines no longer rule the roost. Make them know that !

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           Post #: 113

    RE: Another wasted evening with the OS 91FX - 9/29/2003 2:02:20 AM   
    FLYBOY



    Posts: 8692
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		At least hobbico is good about trying to help fix the problem. I hope we come to a good resolve. I have been happy so far with them. Just waiting for a note back and it hopefully will be resolved.

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           Post #: 114

    RE: Another wasted evening with the OS 91FX - 9/30/2003 2:45:59 AM   
    Ernie Misner


     

    Posts: 3160
    Joined: 7/5/2002
    From: Tacoma, WA, USA
    Status: offline     		Did they (OS) ever fully resolve the peeling liner issue? In my mind they haven't, but perhaps others are no longer leery of peeling liners...?

    Ernie

    (in reply to FLYBOY)
           Post #: 115

    RE: Another wasted evening with the OS 91FX - 9/30/2003 3:08:36 PM   
    FLYBOY



    Posts: 8692
    Joined: 1/7/2002
    From: Missoula, MT, USA
    Status: offline     		I don't know about the liners.

    They did however take pretty good care of me. I am happy with the solution. I wish they would put the needles back in the carbs where they belong or give us the option like some other manufacturers. I really dislike the rear needle. It makes fueling more difficult without a third line and it just isn't as convienient to use. The extra inch from the prop I feel will make people more careless turning it and eventually, they will get their fingers in the prop anyway.

    Good people at hobbico. Been buying from them since they opened, and will continue to do so. They care about their customers.


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           Post #: 116

    RE: Another wasted evening with the OS 91FX - 9/30/2003 3:27:08 PM   
    rajul



    Posts: 6379
    Joined: 6/18/2002
    From: Missouri City, TX, USA
    Status: offline     		Hobbico's not bad at all. They just sent me some additional cones for my TF magnetic balancer, so that I can modify them for my fun-fly props with thin hubs

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