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low idle setting

Old 04-15-2007, 08:43 PM
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willygog
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Default low idle setting

Hi, I have an older 46fx and I need advice, where or rather how do I setup the low idle screw, I need a general starting spot, like 1 and 1/2 turns from all the way out or something along those lines. I had it idleing but it bogged down bad when I cranked it to high speed. usually it stalls out. I turned it in a ways an now I cant get it to start on low idle anymore. Also it sat for a long time so I took it apart and cleaned it out and made sure the piston ring was free. It was seized but its loose now. I have low compression till it warms up then its strong, is that normal for a ringed piston. Its been ten years since this beast ran , It did run ok and cranks up to around 10500 with a 10/6 on it. I just need some advice on that darn idle screw. Anyone care to through out a few suggestions. Thanks in advance.
Old 04-15-2007, 08:50 PM
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Default RE: low idle setting

The only 46FX's that had a ring were the Heli versions

Look down in the carburetor with the throttle wide open. Set the low speed screw to where it is about .040" away from the high speed spray bar
Old 04-15-2007, 08:58 PM
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Trollmaster
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Default RE: low idle setting

Heres one way. Look in your barrel and set the opening to an approximate opening for idle. Now Open the high end a couple turns. This is just to get things into place. Close the low end (idle) screw completely. Attach a fuel tube to the nipple on the carb. Now at the same time, blow into the tube and open the low end screw until you here a hissing noise, then stop. it should now be set well enough to start it up and adjust from their

To ask for a "factory setting" is a legitimate question but considering where people live in the world, factory settings are of no value and this puts you in a good starting point when things get all out of whack
Old 04-15-2007, 11:09 PM
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DarZeelon
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Default RE: low idle setting


ORIGINAL: willygog

Hi, I have an older .46FX and I need advice, on where, or rather how do I setup the low idle screw. I need a general starting spot, like 1 and 1/2 turns from all the way out, or something along those lines. I had it idling but it bogged down bad when I cranked it to high speed. Usually it stalls out. I turned it in a ways an now I can't get it to start on low idle anymore. Also, it sat for a long time so I took it apart and cleaned it out and made sure the piston ring was free. It was seized but its loose now. I have low compression till it warms up then its strong. Is that normal for a ringed piston? Its been ten years since this beast ran. It did run OK and cranks up to around 10,500 with a 10x6 on it. I just need some advice on that darn idle screw. Anyone care to throw out a few suggestions?

Thanks in advance.
Willy,


According to the [link=http://manuals.hobbico.com/osm/50sx-40-46-61-91fx-manual.pdf]OS.46FX manual[/link], the 'factory' setting is 1.5 turns open.

Please follow the instructions as to how to achieve this status.

This manual also gives you more info on how to tweak the low-speed needle/mixture control valve for flight.

It is not the 'idle screw' since it controls the mixture from idle to 75-80% throttle...



10,500 RPM on a 10x6 prop is really lousy; as if your engine is making less than 40% of its normal power.
Old 04-16-2007, 05:36 AM
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willygog
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Default RE: low idle setting

Hey guys great info, I tore that thing apart last night and found a clog in the needle valve. seems there was a little dirt in there or thread or something gooey, anyway cleaned it out again. I will try again later today and see what goes. It may be a heli engine but I got it recc. as an airplane engine, it was really strong. I'm sure it will be again. I just hope I dont need parts as they could be hard to get per OS. Thanks for that manual ! jut what I needed.
Old 04-16-2007, 08:25 AM
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Trollmaster
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Default RE: low idle setting

ORIGINAL: DarZeelon


ORIGINAL: willygog

Hi, I have an older .46FX and I need advice, on where, or rather how do I setup the low idle screw. I need a general starting spot, like 1 and 1/2 turns from all the way out, or something along those lines. I had it idling but it bogged down bad when I cranked it to high speed. Usually it stalls out. I turned it in a ways an now I can't get it to start on low idle anymore. Also, it sat for a long time so I took it apart and cleaned it out and made sure the piston ring was free. It was seized but its loose now. I have low compression till it warms up then its strong. Is that normal for a ringed piston? Its been ten years since this beast ran. It did run OK and cranks up to around 10,500 with a 10x6 on it. I just need some advice on that darn idle screw. Anyone care to throw out a few suggestions?

Thanks in advance.
Willy,


According to the [link=http://manuals.hobbico.com/osm/50sx-40-46-61-91fx-manual.pdf]OS.46FX manual[/link], the 'factory' setting is 1.5 turns open.

Please follow the instructions as to how to achieve this status.


Do as you wish but what I said earlier is nothing knew and done by many. Altitude, climate and half a dozen other factors play an important part of tuning up an engine. Setting the low end at 1.5 turns may work, it may not. If if you cannot draw fuel at 1.5 turns, what do you do? Send it back to hobby services and say,"my engine won't run?" Of course not, You need a baseline to start from and what I suggested will give it too you.

I now many pilots, many will skills far better than me than cannot tune an engine it the plane depended on it. There are lousy pilots who can dial in an engine like a Rolex. Builders who can't fly and flyers who can't build.

From most every thing I've ever read, many engines have specs and techs based on sea level. Well we all don't live their and need to adjust as necessary to make things work. If your living in the Rockies somewhere and you ask what rpms guys are getting on a particular engine/prop? You better make sure the answers you receive are from the same area or you'll be very disappointed and be fooling with that thing for no reason.

I'm not going to debate "Dar" because he is extremely knowledgeable and knows more about this than I do but referring back to the manual is not always the answer


Old 04-16-2007, 08:58 AM
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Default RE: low idle setting

TM,


The baseline is 1.5 turns open.

This is a starting point, which for all OS.46FX/AX engines I have played with, was rich.
But if high nitro is used, it may prove to be too lean.

It is up to the user to know and to understand, by the behavior of the engine, if it is too lean, or too rich, at this starting point and anywhere else.

If the user is not capable of determining if it is too rich, or too lean, so he/she can make the appropriate correction, I believe this person is not entitled to own and to use a model glow engine.

Not all people can have a pilot's license and not everyone who finds it difficult to adjust his/her glow engine, can make it the manufacturer's problem. If one cannot learn how to do this on his own, engines are not for this person. Period!
Old 04-16-2007, 09:42 AM
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Default RE: low idle setting

ORIGINAL: DarZeelon
If the user is not capable of determining if it is too rich, or too lean, so he/she can make the appropriate correction, I believe this person is not entitled to own and to use a model glow engine.
Well if I'd known that more than 50 years ago when I got my first model engine (a British 5cc speed engine) I wonder what hobby I might have taken up? Stamp collecting? No, I didn't know anything about that either. Everyone, except Dar of course, has to start somewhere and learn either by experience or being taught.
Old 04-16-2007, 09:50 AM
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Trollmaster
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Default RE: low idle setting

So I guess the answer to all this is to set the engine up per the manual. If it doesn't run well, then send it in for repair!
Old 04-16-2007, 10:20 AM
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DarZeelon
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Default RE: low idle setting


ORIGINAL: Trollmaster

So I guess the answer to all this is to set the engine up per the manual. If it doesn't run well, then send it in for repair!
TM,


No, this is not the way.
The 'factory settings' are by no way the words of G-d Almighty... They are just a good point, from which the user can start adjusting the engine.

The chance an engine; any engine at all, will run well at these 'factory settings' is nearly absolute zero.

All engines need to be adjusted/tweaked from those 'factory settings', until they run as best as they possibly could.


Only an engine that has been pre-run and pre-adjusted by its manufacturer (Jett??); and only if it is run with the same prop, on the same fuel and in the same ambient condition, and with the tank set up exactly the same, will it run well at the 'factory settings'.

Even then, as this engine wears in, it will need to be tweaked by the user.
Old 04-17-2007, 08:48 PM
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decay
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Default RE: low idle setting

Dar talks like he's from some foreign country!!! Certainly not the attitude at my
flying field, lota guys have buddys to tweek their needles if need be.
But they fly like pros!! Airline pilots don't get out and wrench on jet engines.
Wouldnt that be something, ya land and the pilot gets out , pumps up the tires,
opens the engine hatch & grabs a wrench, opens a radio hatch starts messin
with the wireing!!! HA HA. Maybe thats how they do it where Dars from.
Old 04-18-2007, 12:35 AM
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DarZeelon
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Default RE: low idle setting


ORIGINAL: decay

Dar talks like he's from some foreign country!!! Certainly not the attitude at my
flying field, lota guys have buddys to tweek their needles if need be.
But they fly like pros!! Airline pilots don't get out and wrench on jet engines.
Wouldnt that be something, ya land and the pilot gets out , pumps up the tires,
opens the engine hatch & grabs a wrench, opens a radio hatch starts messin
with the wireing!!! HA HA. Maybe thats how they do it where Dars from.
Decay,


Where is that attitude from and what exactly are you contesting?

When you're an airline pilot there are mechanics that do all the maintainance for you.
It is their job, for which they are paid.


Few R/C flyers, most in serious competition, do have their mechanic/side-kick/helper.
But most R/C fliers in my country know how do their own homework and I believe this is true of most R/C fliers in your country also.

If you want to fly R/C, you better learn how to properly maintain your model and its engine.

And as to my country; you must stand up straight, heels together and solute before saying its name...

Real pilots from my country demolished the Iraqi nuclear reactor in 1981 and managed to fly and to save an F-15 with one wing.
And in the Virginia Tech massacre in your country, the only person witnessed to have done something heroic, was a professor who came there from my country and was a survivor of the holocaust...

Never mock, or redicule my country!


And get your spelling straightened out... There are over eight spelling and grammatical errors in the quoted text...

Use your real name.

Old 04-18-2007, 01:20 AM
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MarkNovack
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Default RE: low idle setting

.46FX idle is very simple to set. Having the throttle body JUST closed, where the apeture just hides the daylight from the induction port, close the needle fully but gently and then open about 3/4 turn. The factory setting of 1.5 turns open from the throttle body JUST closed on .46FX's is very rich in every .46FX I have ever tuned with a sputtery acceleration. If you are using good fuel and a proper plug, as in an OS A3 or #8, acceleration on the .46FX should be perfect and rapid after a 10 second idle period. If it dies when rapidly advancing the throttle, open 1/4 turn at a time until is accelerates perfectly, if it sputters through acceleration, close it 1/4 turn at a time until it accelerates perfectly. I read that you had a clogged up carb at on point, so I'll add if the motor does not run perfectly, then flush the carb and needle valve (it take only a tiny bit of dirt to ruin the tunability), ensure the fuel lines have no holes, try a new plug, and if your fuel is very old... These motors run very, very well. Accept nothing less than perfect acceleration on your .46FX.

The idle screw on the .46FX is not so sensitive, and tiny, 1/16th turns will do little. Just remember that the base setting are figured with the throttle body just closed.

The .46FX, AX, and .50SX are my favorite little 2-strokes because of their simple carburetor and wonderful tunability, ease of use.

Mark

PS: Edited to add; After sitting for ten years, the bearings could be quite corroded causing a drastic loss of high RPM. However, this should not effect the acceleration.

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