O.S. 50 SX air bubbles
10-19-2003, 08:32 PM
#1
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O.S. 50 SX air bubbles
Hi,
I have a new O.S. 50 SX which I am (with the help of the clubs flight instructor)
trying to breakin. We are getting air bubbles in the fuel line between the
remote neadle valve and the carb.
So far:
We have replaced the fuel line.
Check the tank (no foaming).
Check all connections/seals/tighened. (needle valve assembly, and fuel line
connections)
The only mishap we I have had with the engine the airplane fell during transport
and broke the the remote needle valve bracket (attached to the backplate).
I obtained a new back plate from Tower Hobbies and refitted the needle valve
assembly from the damaged back plate.
Any help you can give to solve our mystery air bubbles will be appreciated.
Thanks
Brgds
John Zwart
I have a new O.S. 50 SX which I am (with the help of the clubs flight instructor)
trying to breakin. We are getting air bubbles in the fuel line between the
remote neadle valve and the carb.
So far:
We have replaced the fuel line.
Check the tank (no foaming).
Check all connections/seals/tighened. (needle valve assembly, and fuel line
connections)
The only mishap we I have had with the engine the airplane fell during transport
and broke the the remote needle valve bracket (attached to the backplate).
I obtained a new back plate from Tower Hobbies and refitted the needle valve
assembly from the damaged back plate.
Any help you can give to solve our mystery air bubbles will be appreciated.
Thanks
Brgds
John Zwart
10-22-2003, 02:47 PM
#2
My Feedback: (11)
RE: O.S. 50 SX air bubbles
Air bubbles in the line between the needle and the carb on the .50 SX isn't something we've encountered or heard about before. If the seals are good, there shouldn't be a problem. Is the needle loose in its fitting?
One major source could be vibration-induced fuel foaming in the tank. This puts micro-bubbles in the fuel, which then accumulate at the needle into larger bubbles before they break off and go to the carb.
How's the engine running? If it's set too lean to begin with, it could be running hot, which would then heat the needle assembly to the point where the fuel's being vaporized at the needle. This could also cause the bubbles.
Sorry we don't have an certain answer for you, but this isn't something we've seen on this engine.
One major source could be vibration-induced fuel foaming in the tank. This puts micro-bubbles in the fuel, which then accumulate at the needle into larger bubbles before they break off and go to the carb.
How's the engine running? If it's set too lean to begin with, it could be running hot, which would then heat the needle assembly to the point where the fuel's being vaporized at the needle. This could also cause the bubbles.
Sorry we don't have an certain answer for you, but this isn't something we've seen on this engine.
