91 Fx
08-10-2003, 11:23 AM
#1
Thread Starter
My Feedback: (53)
91 Fx
Ok, I'm having difficulties with this particular engine.....now I'm also running three 140RX with 7B carb 2 32SX 1 61FX ect...you get the point??
This engine is running like a ^%$# very unreliable mixture I have tried different fuels / props / glow plugs / muffler the needle setting is not constant at all...the Engine is installed in one of my UCD 3D, I can make it run fine straight and level...but as soon as I hover for more than 20 seconds it get lean, now I have set the needle quite on the rich side....burbling on take-off and it still got lean in the hover.....what can you guy's do for me?
The engine was purchase at the same time as my first UCD.
This engine is running like a ^%$# very unreliable mixture I have tried different fuels / props / glow plugs / muffler the needle setting is not constant at all...the Engine is installed in one of my UCD 3D, I can make it run fine straight and level...but as soon as I hover for more than 20 seconds it get lean, now I have set the needle quite on the rich side....burbling on take-off and it still got lean in the hover.....what can you guy's do for me?
The engine was purchase at the same time as my first UCD.
08-11-2003, 03:19 PM
#2
My Feedback: (11)
91 Fx
If the engine's running normally in all modes except hover, then a fuel draw difficulty might be suspected. The engine's leaning because fuel pressure goes down when the engine's trying to draw the fuel straight up. We'd expect a similar thing on a long vertical upline.
You may need to use fuel tubing with a larger inside diameter running all the way from the clunk in the tank to the needle valve. This may require drilling-out fittings, and replacing the clunk line.
You may also need to find a way to increase muffler pressure to the tank. Some exhaust systems don't deliver enough pressure to give the engine good fuel flow.
You may need to use fuel tubing with a larger inside diameter running all the way from the clunk in the tank to the needle valve. This may require drilling-out fittings, and replacing the clunk line.
You may also need to find a way to increase muffler pressure to the tank. Some exhaust systems don't deliver enough pressure to give the engine good fuel flow.
08-16-2003, 10:17 AM
#3
Thread Starter
My Feedback: (53)
91 Fx
Well it did not work, still the same, I'm now going to try a few more thing's today at a Fun Fly type day....., since I rarely have problems with my engines but I CAN'T seem to get this one to run smoothly.....maybe I shouldn't hover with my two 46FX or my 50SX....since they could also get lean for nose high maneuver....but the DON'T. I sure would like OS to acknowledged that this engine need to be re-look at in the fuel supply/needle valve area.
I don't remember any of my OS ever behave like this....even the 140RX with worn out bearing work better then this piece......
I have this engines in a UCD...with the instruction saying that this was a good choice of engine..what up with that?
Now using the original muffler...no change.
I don't remember any of my OS ever behave like this....even the 140RX with worn out bearing work better then this piece......
I have this engines in a UCD...with the instruction saying that this was a good choice of engine..what up with that?
Now using the original muffler...no change.
08-18-2003, 08:29 PM
#6
My Feedback: (11)
91 Fx
Daniel,
Check the idle mixture setting. If it's too lean, it can interfere with high-speed fuel flow. Richen the idle a LOT, get the top-end set, and then re-set the idle mixture. If, at a hover setting, the idle mixture's a bit too lean, then it could be causing a restriction in the fuel flow at a medium throttle setting.
Also make sure there's no debris in the carburetor. We sometimes find some fuzz or plastic 'hair' between the needle and the needle seat.
If the needle seems to be leaking air, and you're getting bubbles between the needle and the carb, try removing the needle holder and fuel inlet fitting, removing the fiber washers, and reassembling without them. Sometimes they come out uneven from the factory and could leak.
Check the idle mixture setting. If it's too lean, it can interfere with high-speed fuel flow. Richen the idle a LOT, get the top-end set, and then re-set the idle mixture. If, at a hover setting, the idle mixture's a bit too lean, then it could be causing a restriction in the fuel flow at a medium throttle setting.
Also make sure there's no debris in the carburetor. We sometimes find some fuzz or plastic 'hair' between the needle and the needle seat.
If the needle seems to be leaking air, and you're getting bubbles between the needle and the carb, try removing the needle holder and fuel inlet fitting, removing the fiber washers, and reassembling without them. Sometimes they come out uneven from the factory and could leak.
08-19-2003, 08:48 AM
#8
Thread Starter
My Feedback: (53)
91 Fx
Will try these....some of which I have already done, the engine has a Tettra air filter on.....and yes it was run without to try...I run my 140 RX with these when they fit.
Will let you know
Will let you know
Originally posted by Bax
Daniel,
Check the idle mixture setting. If it's too lean, it can interfere with high-speed fuel flow. Richen the idle a LOT, get the top-end set, and then re-set the idle mixture. If, at a hover setting, the idle mixture's a bit too lean, then it could be causing a restriction in the fuel flow at a medium throttle setting.
Also make sure there's no debris in the carburetor. We sometimes find some fuzz or plastic 'hair' between the needle and the needle seat.
If the needle seems to be leaking air, and you're getting bubbles between the needle and the carb, try removing the needle holder and fuel inlet fitting, removing the fiber washers, and reassembling without them. Sometimes they come out uneven from the factory and could leak.
Daniel,
Check the idle mixture setting. If it's too lean, it can interfere with high-speed fuel flow. Richen the idle a LOT, get the top-end set, and then re-set the idle mixture. If, at a hover setting, the idle mixture's a bit too lean, then it could be causing a restriction in the fuel flow at a medium throttle setting.
Also make sure there's no debris in the carburetor. We sometimes find some fuzz or plastic 'hair' between the needle and the needle seat.
If the needle seems to be leaking air, and you're getting bubbles between the needle and the carb, try removing the needle holder and fuel inlet fitting, removing the fiber washers, and reassembling without them. Sometimes they come out uneven from the factory and could leak.
09-10-2003, 08:07 AM
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RE: 91 Fx
You can also fix it yourself by cutting the needle valve assembly off of the engine and mounting it to the firewall. Since I did this my engine is like night and day! Not one lean run or dead-stick since modifying.
Ian
Ian
09-10-2003, 06:09 PM
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RE: 91 Fx
Joe, I am now pretty sure that the problem is vibration. When I re-mounted the needle-valve it was actually higher than stock. I have had a bunch more flights with NO problems at all.
While investigating my problem a few people told me about the O.S. .46 FX problems. Turned out to be porus metal that allowed air to be sucked through it. The fix was to coat the needled valve casing with clear nail polish-this was an early problem with the first batch released.
Good luck.
Ian
While investigating my problem a few people told me about the O.S. .46 FX problems. Turned out to be porus metal that allowed air to be sucked through it. The fix was to coat the needled valve casing with clear nail polish-this was an early problem with the first batch released.
Good luck.
Ian
09-10-2003, 09:31 PM
#13
RE: 91 Fx
Thanks Ian. I'll try coating it with the clear fingernal polish and if that doesn't work, re-mount the needle valve. Can't hurt to try.
All these people keep telling me the tank center line has to be at the center line of the needle valve. Can that be done with any plane out there? I don't see how without inverting the engine. There is no moving my engine or tank so I'm stuck with what I have...if I stick with the 46FX that is.
Joe
All these people keep telling me the tank center line has to be at the center line of the needle valve. Can that be done with any plane out there? I don't see how without inverting the engine. There is no moving my engine or tank so I'm stuck with what I have...if I stick with the 46FX that is.
Joe
09-10-2003, 10:06 PM
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RE: 91 Fx
ORIGINAL: JoeAirPort
Thanks Ian. I'll try coating it with the clear fingernal polish and if that doesn't work, re-mount the needle valve. Can't hurt to try.
All these people keep telling me the tank center line has to be at the center line of the needle valve. Can that be done with any plane out there? I don't see how without inverting the engine. There is no moving my engine or tank so I'm stuck with what I have...if I stick with the 46FX that is.
Joe
Thanks Ian. I'll try coating it with the clear fingernal polish and if that doesn't work, re-mount the needle valve. Can't hurt to try.
All these people keep telling me the tank center line has to be at the center line of the needle valve. Can that be done with any plane out there? I don't see how without inverting the engine. There is no moving my engine or tank so I'm stuck with what I have...if I stick with the 46FX that is.
Joe
Ian
