DLE 111 Carb Adjustment Problems
08-28-2011, 11:32 AM
#1
DLE 111 Carb Adjustment Problems
I'm having some problems getting my new DLE 111 to run properly. I have been running gas engines ever since Quadra introduced the Q38 but this is my first big twin gasser. I have done searches and have read through all of the forums I could find on the DLE 111 and have tried all of the ideas and solutions suggested. I'm hoping someone has some ideas that I have not tried or is this normal for a twin cylinder gas engine of this size.
The history:
The engine was purchased from Tower Hobbies about a year ago and was mounted and test run for a few minutes right after I got it. After a few minor adjustments it settled down and ran OK. I was getting about 6400 rpm on a Zoar 27x10 prop. I ran about 16 ounces of 30-1 93 octane no ethanol gas mixed with Pennzoil Air cooled oil. I ran the fuel out of the carb and stored the engine until I was ready to install it on my 1/3 scale Bird Dog about a month ago. It is now installed and I have been trying to get the carb set to give me a smooth idle, good transition, and a slightly rich high end for beak in. Again I am running 30-1 Pennzoil and 93 Octane gas with no Ethanol.
I downloaded The new manual from Hobbico which is a bit better than the poorly translated instruction sheet I got with the engine. The engine is installed and set up in accordance with the manual.
The manual says to set the low speed needle at 1.25 turns and the high speed at 1.5 turns. This set up results in the idle being way too lean. The engine will not transition and the engine rpm increases on it's own from idle. Setting the idle needle at about 2 turns results in very good transition but a rough idle. Anything between this setting and the recommended 1.25 turns results in the above problems.
With the low speed set at 2 turns and the high speed set at 1.5 turns the engine transitions and runs very strong at high end, but I can't get the engine to richen much more than a few hundred RPM no matter how far out I turn the high speed needle. It will never go into a rich 4 cycle. The cylinder temps are about 220 degrees F with the outside air temps at 100F. I'm told this is about what I should expect.
I have checked all of the fuel delivery system and everything is good. All tubing is Dubro X-large (5/32" ID) tubing running through the Sullivan large fuel tank cap and fittings. There are no restrictions between the tank and carb.
I have checked and cleaned the screen in the carb for the plug cement. It was partially plugged. While I had the carb open I clean up the remaining plug cement, checked the metering lever to make sure it was set right, and then cleaned everything out with carb cleaner spray. I inspected all of the diaphragms and gaskets and carefully re-assembled the carb.
I have attached a photo of the engine installation and the exhaust set-up for information.
Short of sending the engine back to Tower or replacing the carb, is there anything else I need to look at or is this normal for the DLE 111?
The history:
The engine was purchased from Tower Hobbies about a year ago and was mounted and test run for a few minutes right after I got it. After a few minor adjustments it settled down and ran OK. I was getting about 6400 rpm on a Zoar 27x10 prop. I ran about 16 ounces of 30-1 93 octane no ethanol gas mixed with Pennzoil Air cooled oil. I ran the fuel out of the carb and stored the engine until I was ready to install it on my 1/3 scale Bird Dog about a month ago. It is now installed and I have been trying to get the carb set to give me a smooth idle, good transition, and a slightly rich high end for beak in. Again I am running 30-1 Pennzoil and 93 Octane gas with no Ethanol.
I downloaded The new manual from Hobbico which is a bit better than the poorly translated instruction sheet I got with the engine. The engine is installed and set up in accordance with the manual.
The manual says to set the low speed needle at 1.25 turns and the high speed at 1.5 turns. This set up results in the idle being way too lean. The engine will not transition and the engine rpm increases on it's own from idle. Setting the idle needle at about 2 turns results in very good transition but a rough idle. Anything between this setting and the recommended 1.25 turns results in the above problems.
With the low speed set at 2 turns and the high speed set at 1.5 turns the engine transitions and runs very strong at high end, but I can't get the engine to richen much more than a few hundred RPM no matter how far out I turn the high speed needle. It will never go into a rich 4 cycle. The cylinder temps are about 220 degrees F with the outside air temps at 100F. I'm told this is about what I should expect.
I have checked all of the fuel delivery system and everything is good. All tubing is Dubro X-large (5/32" ID) tubing running through the Sullivan large fuel tank cap and fittings. There are no restrictions between the tank and carb.
I have checked and cleaned the screen in the carb for the plug cement. It was partially plugged. While I had the carb open I clean up the remaining plug cement, checked the metering lever to make sure it was set right, and then cleaned everything out with carb cleaner spray. I inspected all of the diaphragms and gaskets and carefully re-assembled the carb.
I have attached a photo of the engine installation and the exhaust set-up for information.
Short of sending the engine back to Tower or replacing the carb, is there anything else I need to look at or is this normal for the DLE 111?
08-28-2011, 12:48 PM
#3
RE: DLE 111 Carb Adjustment Problems
ORIGINAL: KenLambert
It could be the exhaust being to restricking. Thats a lot of twist and turns with that small tubing. My opinion only.
It could be the exhaust being to restricking. Thats a lot of twist and turns with that small tubing. My opinion only.
Thanks for the feed back.
That is why I posted the photos of the exhaust. The outlet size of the DLE silencers is 25mm or just under 1". I used the K & S thin wall 25mm SS tubing to plumb the exhaust to try to eliminate any restrictions. The elbows are long sweep. It will be an easy task to drop the tail pipes and see if that helps. I'll post the results.
Gaines
08-28-2011, 01:20 PM
#4
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RE: DLE 111 Carb Adjustment Problems
Gaines,
Why on earth would you want to go the engine into a rich 4-cycle????
The larger the engine, the less margin there is for carbs to achieve that extremely rich fuel to air ratio. As long as there is a rich drop-off condition of about 50 rpm you are just fine and good to go, and the carb will allow all settings from best power, to best economy. The story changes if you cannot set the engine rich (not necessarily 4-stroking) without having the idle needle too wide open. In that condition, the carb clearly needs some corrective actions, or you must apply exhaust pressure to the regulating membrane plenum chamber.
Why on earth would you want to go the engine into a rich 4-cycle????
The larger the engine, the less margin there is for carbs to achieve that extremely rich fuel to air ratio. As long as there is a rich drop-off condition of about 50 rpm you are just fine and good to go, and the carb will allow all settings from best power, to best economy. The story changes if you cannot set the engine rich (not necessarily 4-stroking) without having the idle needle too wide open. In that condition, the carb clearly needs some corrective actions, or you must apply exhaust pressure to the regulating membrane plenum chamber.
08-28-2011, 01:40 PM
#5
RE: DLE 111 Carb Adjustment Problems
ORIGINAL: pe reivers
Gaines,
Why on earth would you want to go the engine into a rich 4-cycle????
The larger the engine, the less margin there is for carbs to achieve that extremely rich fuel to air ratio. As long as there is a rich drop-off condition of about 50 rpm you are just fine and good to go, and the carb will allow all settings from best power, to best economy. The story changes if you cannot set the engine rich (not necessarily 4-stroking) without having the idle needle too wide open. In that condition, the carb clearly needs some corrective actions, or you must apply exhaust pressure to the regulating membrane plenum chamber.
Gaines,
Why on earth would you want to go the engine into a rich 4-cycle????
The larger the engine, the less margin there is for carbs to achieve that extremely rich fuel to air ratio. As long as there is a rich drop-off condition of about 50 rpm you are just fine and good to go, and the carb will allow all settings from best power, to best economy. The story changes if you cannot set the engine rich (not necessarily 4-stroking) without having the idle needle too wide open. In that condition, the carb clearly needs some corrective actions, or you must apply exhaust pressure to the regulating membrane plenum chamber.
I'm glad you came to my rescue. It does look like I was trying to achieve something that is not going to happen with these larger engines. Old habits are hard to break. I have been able to back off of the peak RPMs of about 6300 to as low as 5850. Using your calculator, that is still a respectable 46 pounds of static thrust. Should pull the 55 pound Bird Dog around just fine. That was with the low end set at 2 turns out. I just ran it again and was able to lean the low end to get a little better idle with the high end out at about 1.75 turns and still got good transition. I will quit worrying and go back to your carb adjustment instructions and just go fly the thing.
Thanks for your help.
Gaines
