Low mixture Engine question
10-14-2008 | 02:51 PM
#1
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From: Timbukto
Low mixture Engine question
For some reason, I moved the low mixture needle valve and don't think I got it back into the right place. It seems that if I have the engine running at idle and the trim in the middle the engine will stop when I trim it all the way down, but the engine seems to bang a little bit and it looks like sometimes the engine starts and then starts again all within milliseconds. I also get engine stops mid-flight.If I change the control rod so that the engine idles faster, I cannot shut the engine down.
Currently, I am just moving the trim up so that it runs smoother. What should I do?
Currently, I am just moving the trim up so that it runs smoother. What should I do?
10-14-2008 | 02:55 PM
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From: Poolesville, MD
RE: Low mixture Engine question
It's still too rich.
Because of the excess fuel the engine is continuing to run after you close off the throttle ... btw you also have a bit of an air leak too!
That extra fuel is mixing with air that is getting by which is what is keeping the engine running.
A faster idle should NOT affect the engine in flight however, something else is amiss too...
Make sure you check the tuning completely and perform pinch tests and nose up/down pinch tests too!
Because of the excess fuel the engine is continuing to run after you close off the throttle ... btw you also have a bit of an air leak too!
That extra fuel is mixing with air that is getting by which is what is keeping the engine running.
A faster idle should NOT affect the engine in flight however, something else is amiss too...
Make sure you check the tuning completely and perform pinch tests and nose up/down pinch tests too!
10-14-2008 | 03:03 PM
#3
RE: Low mixture Engine question
hard to tell from your description is it a 2 stroke or 4?sounds rich trial and error will tell you more than any thing,turn the low speed needle in 1/8 of a turn and see what happens if it dies immediately it is too lean if it runs a bit better turn in another 1/8 turn and see what happens.obviously if it dies immediatly you need to back it out to richen the mixture.actually the way you have it set is the way I prefer .to be able to shut the engine off on low trim and able to adjust the idle to a reliable sow point before take off but I have analog not digital trims
10-14-2008 | 05:50 PM
#4
RE: Low mixture Engine question
Make sure that the limiter screw on top, allows the barrel to fully close.
Check the cleanness of the little hole at front, if your carburetor has it.
Save the position of the low mix screw in your mind, by turning it all the way in.
Then unscrew it completely and clean the tip and the seat in the body.
Screw it back and try again.
Tune the thing 1/8 of a turn at a time, running the engine at full rpm for just few seconds before each pinch test.
Check this article:
http://webpages.charter.net/rcfu/Hel...s/TVAProc.html
Regards!
