nitro engine running slightly rich with needle valve fully closed

by giles
(cornwall, UK)

The engine will only run properly when the needle valve is fully closed. A few clicks open and then its too rich. But then it leans out too much in flight.

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nitro engine running slightly rich with needle valve fully closed

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Nov 22, 2009
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running fine now with orignal carb
by: giles

put the original carb on and all is fine . I didnt use the original carb in the first place as would have to modify frame.

May 04, 2009
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Too rich closed
by: Anonymous

Maybe you have the low end needle way too rich?

Apr 06, 2009
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SX?
by: Anonymous

Is SX the brand of the engine?

Never heard of that one...

I would imagine using a carb designed for a different size engine would present some problems...

Apr 06, 2009
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carb from sx12
by: giles

Forgot to mention the carb is off a sx12 engine. WHere the engine i am running is a 18. but i am sure this was not a problem.

The only thing i had to do was drill the carb for a screw to hold it on as no pinch bolt. If there is an air leak then surly it would run lean with needle valve open a few turns. the needle valve looks fine.

I have ordered some gasget sealent so will try that.

Apr 05, 2009
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maybe bad valve?
by: Matt

It sounds to me that your high speed needle valve may be the culprit.

Has this engine ever been involved with a crash?

The engine shouldn't really run much at all with the needle vale all the way closed.

I would suggest removing the high speed needle by turning it all the way out. Make sure it's not bent or damaged. Make sure there is no debris or anything in there.

If you do find that the needle is damaged, you can usually find the part number in your owners manual and order a new one from where ever you bought the engine.

Please let me know what you find!

Matt