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O.S. 40LA adjustment question??

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O.S. 40LA adjustment question??

Old 09-13-2010, 09:21 PM
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CGCINC
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Default O.S. 40LA adjustment question??

I have searched and search but I cannot find the proper or Factory setting for this screw....and what it is for???? Idle?

The motor runs smooth but dies at an idle. This screw was turned out about 6-7 turns when I got it.

Old 09-13-2010, 09:32 PM
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w8ye
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Default RE: O.S. 40LA adjustment question??

The factory setting is half way across the hole in the front of the carburetor
Old 09-13-2010, 09:33 PM
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Default RE: O.S. 40LA adjustment question??

That's an air bleed screw..it is for adjusting the idle mixture.
Typically, a ball park setting would be with the screw blocking half way across the little hole in front of the carb.

Opening it further leans the idle mixture, and vice-versa...
Old 09-13-2010, 11:33 PM
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Default RE: O.S. 40LA adjustment question??

I use a very small pin in the hole so I can feel how far out is is going in relation to the air bleed hole. Like 8 said, the starting point is about half opened. You adjust the high end first then the low end.
Old 09-14-2010, 06:39 AM
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Ed Smith
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Default RE: O.S. 40LA adjustment question??

There is an easy way to adjust any idle screw. Turn the screw all the way in until it stops. Now there is only one way to turn it to get it right, no guesswork . SO, set the high speed needle and gradualy unscrew the low speed until it is correct.

Ed S
Old 09-14-2010, 07:52 AM
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Default RE: O.S. 40LA adjustment question??

Thanks.... I think its close to half way.
When you close the throttle all the way should it die or still idle? This is not in a plane, just on a running stand...
Old 09-14-2010, 08:04 AM
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Default RE: O.S. 40LA adjustment question??

To close the throttle all the way, the engine should quit.

The air hole in the front of the carb on the air bleed carbs is usually only exposed to the inside of the carb throat at the idle position which is not completly closed
Old 09-14-2010, 08:10 AM
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Default RE: O.S. 40LA adjustment question??

Here's the owner's manual for the engine

http://manuals.hobbico.com/osm/40-46-65la-manual.pdf
Old 09-14-2010, 09:02 AM
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Default RE: O.S. 40LA adjustment question??


ORIGINAL: w8ye

Here's the owner's manual for the engine

http://manuals.hobbico.com/osm/40-46-65la-manual.pdf
I've got that but it only talks about the needle valve.

I see the little hole in front now that I looked closer, thanks for all the help guys! (gals too??)
Old 09-14-2010, 09:29 AM
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Default RE: O.S. 40LA adjustment question??

I've got that but it only talks about the needle valve.
Page 25.
Old 09-14-2010, 10:29 AM
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Default RE: O.S. 40LA adjustment question??


ORIGINAL: Top_Gunn

I've got that but it only talks about the needle valve.
Page 25.
DOH! lol..Thanks
Old 09-14-2010, 01:31 PM
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Default RE: O.S. 40LA adjustment question??

Hi!
That little hole is where the engine sucks additional air at low throttle opening. I should be set at half open as standard. If engine does not idle perfectly at this setting adjust it slightly ...most of the time... open it a turn or more.
But! To have the engine run good at low throttle the throttle drum must be set correctly.
A correct way of setting is to have the drum open just 1,5-2mm at idle! At that setting your engine should idle at around 2000-2500 rpm if all is correct.
The OS LA .40 engines are dead reliable on all prop sizes but as it is no racing engine it can be run on fairly large props like 11x5 and 11x6 APC or RAM. These props are suitable on slow flying high winged trainers.

For fuel anything between 5-15% nitro works well, In fact these engines are dead reliable on just 5% nitro!

See to that you use OS 8 or Enya 3 glow plugs...ofcourse there are others that work well too but those are considered good sport glow plugs suitable for most two stroke engines.

Also ...do not use too large fuel tank, that will only invite trouble . A suitable tank seize for the OS La .40 and .46 is a 240cc tank (8oz)...and be certain to mount it according to "the tank mounting rule"!

Old 09-14-2010, 02:03 PM
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Default RE: O.S. 40LA adjustment question??


ORIGINAL: jaka

Hi!
That little hole is where the engine sucks additional air at low throttle opening. I should be set at half open as standard. If engine does not idle perfectly at this setting adjust it slightly ...most of the time... open it a turn or more.
But! To have the engine run good at low throttle the throttle drum must be set correctly.
A correct way of setting is to have the drum open just 1,5-2mm at idle! At that setting your engine should idle at around 2000-2500 rpm if all is correct.
The OS LA .40 engines are dead reliable on all prop sizes but as it is no racing engine it can be run on fairly large props like 11x5 and 11x6 APC or RAM. These props are suitable on slow flying high winged trainers.

For fuel anything between 5-15% nitro works well, In fact these engines are dead reliable on just 5% nitro!

See to that you use OS 8 or Enya 3 glow plugs...ofcourse there are others that work well too but those are considered good sport glow plugs suitable for most two stroke engines.

Also ...do not use too large fuel tank, that will only invite trouble . A suitable tank seize for the OS La .40 and .46 is a 240cc tank (8oz)...and be certain to mount it according to "the tank mounting rule"!

Ok, Thanks.
Right now I have it mounted on a stand with an 8oz. fuel tank just so I can run it. This winter I will probably put it in a small plane to get my feet wet with Nitro.

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