O.S. .46 engine problem
05-22-2004 | 09:18 AM
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From: East Moline, IL
O.S. .46 engine problem
What causes the engine to hesitate when going from 1/2 to full throttle during flight? Not very quick response time. And when I shut off the engine via the throttle trim and the carb is completely closed, there is fuel sitting in the carb. I read the thread on engine tuning and what is the 2 stroke and 4 stroke sound I'm looking for? How do I know if it is too lean (too lean as in damaging the engine). Can't get to the field today so I was going to try to work on the engine but I am a complete noob.
05-22-2004 | 09:49 AM
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From: Coon Rapids, MN
RE: O.S. .46 engine problem
First, is this an OS 46FX or an OS 46LA - that will determine how to deal with this problem.
If it's an FX:
Most "LIKELY" you are looking at an engine with a rich setting for the low speed needle valve, or running very rich on the high speed needle. This is not hard to fix, but being new you might want to wait until you can get some help doing it. An experienced flyer will only need a few minutes to make the adjustments.
The low speed needle valve is a recessed screw inside the shaft your throttle control arm is on. I have three of these engines and each responds differently to adjusting this screw. On one of these engines it seems like all I have to do is place the screw driver in the screw slot and lean or turn very lightly on the screw to make a difference. On the others I only turn it an 1/8th of a turn. DO NOT DO THIS WITH THE ENGINE RUNNING!!
Also, make sure you have the high speed needle set right before you adjust the low speed needle. But seriously, I was much better off having experience help with this the first times I did it than going alone. It's easy to get it "ALMOST" right, and then have problems with a too lean engine in the air.
If you have an LA you use an "AIR BLEED SCREW" to make adjustments and I will leave advice on that to another with more experience as I've not had to do much with my one LA.
I would hope you can get experienced help with this before you fly. Good Luck
DickB
If it's an FX:
Most "LIKELY" you are looking at an engine with a rich setting for the low speed needle valve, or running very rich on the high speed needle. This is not hard to fix, but being new you might want to wait until you can get some help doing it. An experienced flyer will only need a few minutes to make the adjustments.
The low speed needle valve is a recessed screw inside the shaft your throttle control arm is on. I have three of these engines and each responds differently to adjusting this screw. On one of these engines it seems like all I have to do is place the screw driver in the screw slot and lean or turn very lightly on the screw to make a difference. On the others I only turn it an 1/8th of a turn. DO NOT DO THIS WITH THE ENGINE RUNNING!!
Also, make sure you have the high speed needle set right before you adjust the low speed needle. But seriously, I was much better off having experience help with this the first times I did it than going alone. It's easy to get it "ALMOST" right, and then have problems with a too lean engine in the air.
If you have an LA you use an "AIR BLEED SCREW" to make adjustments and I will leave advice on that to another with more experience as I've not had to do much with my one LA.
I would hope you can get experienced help with this before you fly. Good Luck
DickB
05-22-2004 | 10:04 AM
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RE: O.S. .46 engine problem
ORIGINAL: RoNeRiC
>What causes the engine to hesitate when going from 1/2 to full throttle
>during flight? Not very quick response time.
The low end (idle screw) is not set properly AND/OR you may have an airleak. If you have bubbles in the fuel line while transitioning you have an air leak in the fuel line. The idle screw plays a large part until you get to ABOUT 1/2 throttle.
>And when I shut off the engine via the throttle trim and the carb is completely
>closed, there is fuel sitting in the carb. I read the thread on engine tuning
>and what is the 2 stroke and 4 stroke sound I'm looking for?
The 2 stroke sound is the "screaming" of the engine. The 4 stroke sound is more like a "blubbering" - similar to when the engine is very rich and at an idle. When you go from the 2 stroke to the 4 stroke the change in sound is distinctive. The engine smooths out. It is kind of difficult to describe. Once you hear it though, you will know the difference.
>How do I know if it is too lean (too lean as in damaging the engine).
With the engine at full throttle, point the plane straight up. If the engine dies, it is too lean and you need to open the HIGH SPEED needle valve a little (richen it up). I suggest doing this in 1/8 turn increments. If the engine speed stays the same, or picks up slightly, the HIGH SPEED needle is set OK. Remember to set the high speed needle about 300 rpm LESS than wide open since the engine will "unload" in the air and speed up a little.
FWIW - I recommend using SOME castor oil (about 3 oz per gallon) in your fuel. The castor helps protect the engine from lean runs and the internal residue helps protect against rust. If your fuel is a 100% synthetic oil, I would add some castor oil. If it is a mix of synthetic/castor oils, see what the percentage of castor is and then ask if any additional castor should be added.
Can't get to the field today so I was going to try to work on the engine but I am a complete noob.
>What causes the engine to hesitate when going from 1/2 to full throttle
>during flight? Not very quick response time.
The low end (idle screw) is not set properly AND/OR you may have an airleak. If you have bubbles in the fuel line while transitioning you have an air leak in the fuel line. The idle screw plays a large part until you get to ABOUT 1/2 throttle.
>And when I shut off the engine via the throttle trim and the carb is completely
>closed, there is fuel sitting in the carb. I read the thread on engine tuning
>and what is the 2 stroke and 4 stroke sound I'm looking for?
The 2 stroke sound is the "screaming" of the engine. The 4 stroke sound is more like a "blubbering" - similar to when the engine is very rich and at an idle. When you go from the 2 stroke to the 4 stroke the change in sound is distinctive. The engine smooths out. It is kind of difficult to describe. Once you hear it though, you will know the difference.
>How do I know if it is too lean (too lean as in damaging the engine).
With the engine at full throttle, point the plane straight up. If the engine dies, it is too lean and you need to open the HIGH SPEED needle valve a little (richen it up). I suggest doing this in 1/8 turn increments. If the engine speed stays the same, or picks up slightly, the HIGH SPEED needle is set OK. Remember to set the high speed needle about 300 rpm LESS than wide open since the engine will "unload" in the air and speed up a little.
FWIW - I recommend using SOME castor oil (about 3 oz per gallon) in your fuel. The castor helps protect the engine from lean runs and the internal residue helps protect against rust. If your fuel is a 100% synthetic oil, I would add some castor oil. If it is a mix of synthetic/castor oils, see what the percentage of castor is and then ask if any additional castor should be added.
Can't get to the field today so I was going to try to work on the engine but I am a complete noob.
05-22-2004 | 10:12 AM
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From: Lusby,
MD
RE: O.S. .46 engine problem
Is the "delay" you're talking about only in flight? If so, you may be experiencing the amount of time it takes for the sound to reach you after you make the input.... just a thought!
05-22-2004 | 11:44 AM
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From: Wayland, MI
RE: O.S. .46 engine problem
ORIGINAL: RoNeRiC
How do I know if it is too lean (too lean as in damaging the engine).
How do I know if it is too lean (too lean as in damaging the engine).
Dave
05-22-2004 | 05:46 PM
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From: East Moline, IL
RE: O.S. .46 engine problem
It's a FX.
My fuel is SIG 20% oil (50% castor-50%syn) 10% nitro
I will try the pinch test.
When I advance the throttle it puts out smoke. (Dolsen, typing in all caps is considered yelling)
I know it's not the delay in sound because I can float the plane in like I'm going to land it and then hit the throttle when the plane is right in front of me.
Thanks for the help guys. I'm not intimidated when it comes to tinkering with it, just do not want to burn up my engine. I broke it in and it has about 10 flights on it. Would because it's still new be the reason for this?
My fuel is SIG 20% oil (50% castor-50%syn) 10% nitro
I will try the pinch test.
When I advance the throttle it puts out smoke. (Dolsen, typing in all caps is considered yelling)
I know it's not the delay in sound because I can float the plane in like I'm going to land it and then hit the throttle when the plane is right in front of me.
Thanks for the help guys. I'm not intimidated when it comes to tinkering with it, just do not want to burn up my engine. I broke it in and it has about 10 flights on it. Would because it's still new be the reason for this?
05-22-2004 | 09:29 PM
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My Feedback: (17)
RE: O.S. .46 engine problem
Yeah, that might do it. Sounds to me like you're rich, but without actually hearing it I couldn't say for sure. Am getting aquainted with it's son, the AX, and will say if that engine is on the rich side, it will definetly hesitate from idle to full throttle. And you do want to wait untill you get it good and broke in before you lean it all the way out, and then and only then can you really set up your idle.
Andy
Andy
05-23-2004 | 09:45 AM
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RE: O.S. .46 engine problem
The SIG fuel (20% 50/50 oil) should provide protection from a lean run.
If it putting out smoke when you advance it, it is rich (or has been idling for awhile). Lean your idle screw. Do this in 1/8 turn increments, WITH THE ENGINE SHUT OFF, and restart and try the transition again. Do this until it transitions smoothly. You MAY have to redo the high speed needle again (if you do, recheck the transition and adjust if needed - the idle will only require a tiny adjustment, if any).
If it putting out smoke when you advance it, it is rich (or has been idling for awhile). Lean your idle screw. Do this in 1/8 turn increments, WITH THE ENGINE SHUT OFF, and restart and try the transition again. Do this until it transitions smoothly. You MAY have to redo the high speed needle again (if you do, recheck the transition and adjust if needed - the idle will only require a tiny adjustment, if any).
