I was running one of my DLE20 yesterday in a Hangar 9 ultra lite stike before flying it for the first time in about two years and noticed that from approx. mid range there was very little increase in rpm's. Is this normal?

Yes that is somewhat normal for all engines that use a carb with a throttle plate. It varies quite a bit though depending on the size of the carb venturi compared to the size of the engine. You can resolve the issue by adding differential to the throttle linkage and / or by using a throttle curve in your transmitter. There has been much written about this here and in other forums. A few searches should get you more info than you ever wanted to know.

How much difference between the carb on a DLE20 and a DLE30? I have a used DLE30 that is in a P-47, which is in for repair after striking a roof! My Bad, but only because the engine was running poorly at low to mid throttle and I was afraid it was going to quit and rushed the landing.

So, what happens is WOT or thereabouts, engine runs great, but anywhere between idle and mid throttle it surges and/or runs rough. No hesitation from idle to WOT, or any strange high/low idles like the DLE20 is known for. Is this because LSN or HSN is too rich, or both? There is a lot more discharge from the exhaust on the 30 than there is on the 20 even considering the 10cc displacement.

At 1/4 throttle, it would surge enough to cause the plane to porpoise if that gives some idea what it does.

The carb on the DLE 30 and 55 are one in the same. The 20cc has a smaller bore. You might try a carb kit to make them run better. I get mine on Ebay. K10-WAT for the DLE 20 and a K20-WAT for the 30 and 55. There are plenty of videos on Youtube covering the rebuild and it's not difficult.

I have two DLE 20's. The first one I bought in May 2015,the second one in April 2016. The first one serial # F17868 was a problem right out of the box. Being my first gas I blamed it on teething problems. It took 5, 14 oz.tanks on a test stand to get it run. I put it in a Great Planes Super Sky Bolt. It worked perfectly for 15 flights before it quit in mid flight. I checked it out on the test stand and could not find any thing wrong it run through 4 tanks of fuel. Put it in a Phoenix Models T-34 first flights went great one minute and fifteen seconds in to the third flight it quit dead. It didn't seize it turns over freely. The second engine serial # F18966 started on the third blip of the starter. have it in the 2001 original Hanger 9 Super Cub I have over thirty flights on it and I'm using the DLE plug that can with the engineThe first engine I changed to the CM-6 plug everyone has been raving about seen no difference. Baffled!

Have you tried swapping out the ignition between them? There are a few things that will cause an engine to quit in flight, first, and most likely cause, too lean a mixture. What works good on the ground doesn't always work good in the air. Second would be cooling, again, what works good on the ground, doesn't always work in the air. Third, glitchy ignition box, and these are the worst to chase. Finally, and most rare, carb icing, or turbulence at the venturi.

The second and fourth can be mitigated with proper baffling, the first is just a matter of chasing needles until you get the most reliable idle, transition and WOT. The third can only be figured out by a swap out. My DLE20 is also finicky, it can run great for a few flights one day, and thinking you got the needles nailed, doesnt run well at all a week later. It is a few years old and has the funky ignition box that high idles then transitions down, making landings a PITA.

Hi Guys
I'm having trouble tuning my DLE 20. It seems OK on the ground, W.O.T. is about 8500 on an APC 17X6 and idle is consistent but a little rough as I believe is normal.
Transition is a little slow but Iv'e only had about 3/4 of a gallon through it so not broke in yet.
Yesterday on landing I was a little short of the runway and needed a little throttle to bring the model on a bit. I was at idle at the time so I increased the throttle a few clicks and nothing happened, a few clicks more and still nothing.
The engine didn't seem as if it was going to quit but it wasn't increasing RPM either. I tried it on the ground later and all seems OK. Any advice would be appreciated.

You need a few more gallons through it before it will run consistently. 3/4 is not enough. You may want to richen the needles just a touch.

Carb ice wasn't the problem it was a 90 + day humidity was about 18% typical day here in southern NM. I will take your advice and switch out the electronics. the strange part is both times it was not the first flight of the day. With 67k plus hours in full scale never had an engine failure thank goodness it happened with one that I wasn't sitting behind a windshield.

I should have said 6700 + hours.

I have a problem with my DLE 20 and after searching and searching I can't seem to find the same one so here it is:

Mine won't idle low enough and I can't kill it with throttle trim.

I took it apart again and the butterfly is tight and the reeds and everything look fine. I did notice tho that the throttle arm hits the engine case when trying to close fully. It's not actually the arm its the machine screw part of the ball link that is in the throttle arm. However, it appears to still close all the way as is and the high idle/can't kill with trim is a new issue (same ball link).

I was thinking about just buying a new carb for 40 bucks but I figured I'd see what the experts have to say?

Thanks so much,
Aaron

Double check the travel (throttle butter fly) using the servo. I had the same problem it was my linkage . With the cowling off bring it to idle using the servo then see if you can get the idle lower by closing the the throttle by hand. Might save 40 bucks

Thanks for the reply and I did try that. I can't kill the engine or get the idle low with just the arm and no servo.

Its a gasser you are supposed to kill it with ignition control, I would be pleased for it to stay with a good idle when throttle closed, no one wants a dead stick anyway.
Think about it !!!!!!!!!!

Wow thank you I can't believe I didn't think to just think about it. Ha ha

I also had problems with the DLE20 throttle arm linkage hitting the crank case. I ended up using a z-bend in some 256 rod, and was able to bend it so that it would clear the crank case. Another option might be to use a different throttle arm (one that tightens from the side instead of the overhead screw). Another possible cause for the high idle is that the throttle plate is not exactly centered, so when you think it's closed there's actually still a gap, letting air in. This is common in these DLE's. The plate might just be off center enough so that you can't see it (specially with the internal positioning of that plate. Will have to take the carb off to do this). Try loosening the throttle plate screw and reseating the plate, then retighten. (this can happen with the choke plate, too.)

A high idle in general is another common problem with the DLE 20's (or used to be - I haven't bought a new one in a few years). If you richen the low end to get the idle down it bogs the engine down. Some have said that the fix is to buy an EI for a different model DLE, like for the DLE 55. Downside - that's $75. Or get a generic RCExel EI for $50. Another option - use your "throttle down" function, where you fly with a higher idle, but cut the idle down another 2-3% just before landing. This very-low idle might kill the engine in a minute, but it's just enough to land the plane and start taxiing, then you can flip the toggle switch back to higher idle in time to keep the engine running while it taxis back to you.

btw - you should also have a remote EI kill switch on all of your gassers, so you don't need to kill the engine with the throttle. And \ or use a choke servo. Many fields require a remote kill for gassers, for safety. With all of the vibration of a gas engine it's not unheard of to lose a throttle linkage in air, and flying around at 1/3 throttle for 25 mins waiting for the engine to die is not fun.

Thanks for the reply...I think I'll try re-centering the throttle plate. That's the only thing that seems like it would cause the high idle to happen out of nowhere.

For the record, this thing is almost 4 years old and ran perfectly until the high idle thing. I do have an opti kill plus a charge/on/off switch in the fuse. I can shut it off at any time via the ignition just saying the unable to shut it off with trim is new and part of the high idle.

And to the smart ass guy, you try landing with an idle high enough to move the plane thru grass when she's on the ground cuz I'm not going to...I can crash on my own not gonna risk it with an engine not running right.

Oh I do beg your parden, but you did not say the idle was such that the aircraft would fly when the throttle was closed only high idle. Also I was not trying to be a smart arse but just giving possible solutions that you may have not known about. I do not know your level of expertise and so I gave the basic answers.
I would assume also that you would have checked the carb for all sorts of problems other than the throttle arm after finding it manually would not shut down the motor.
There was no call label me a smart arse, I just suggested you think about what I said. There are many people who fly with out an electronic kill switch which is a basic safety issue.
Any how I will drag my sorry smart arse off and think of something else to be smart about, but I do hope you can resolve your high idle problem quickly.
Fly safe.

I didn't say it would fly with the throttle closed because it won't but it definitely likes to move on the ground at the lowest possible idle speed I can get.

I took it all apart and don't see any torn gaskets or crud anywhere. The reeds look good, the choke and throttle look good. There has to be something going on but I don't know what it is which is why I posted. And I don't have much expertise at all...can tune it and clean it but not truly sure how it all works.

Oh well, I think I'll try a carb kit and see what that does...or maybe a new carb.

Anyway sorry Clive for calling you a smart ass, it came off that way when I read your reply...still does.

Ok I suppose I could have put it better.

My suggestion would be to find someone at your club that uses gassers (if you are in a club) and get them to look at it before throwing money at it.

There are many reasons for high idle....possible air leak between carb and motor the list can be quite long.

Any how I thank you and accept your apology and I too apologise to you.

If your idle used to be fine then it could be the loose throttle plate issue, or it might just be the colder winter air. Colder air is denser and so needs more fuel to maintain the correct fuel\air ratio. I have to adjust most of my gassers for seasonal changes. Have you tried richening the low end? Or it could be that you need to do a carb rebuild - if you haven't done that in four years then you probably do need it. The pumps \ membranes loose elesticity over time (due to the methanol in gas), so don't perform as they used to. If you haven't done it it's very easy. The kits themslves are around $8. I believe the kit for this carb is the Walbro K20. Lots of useful videos on Youtube. While you're at it you might as well check the tubing inside your tank. Tygon usually stiffens after 2 seasons.

I think microdon has it. Seasonal change. You're likely running in a little cooler temps, causing it to run a hair on the lean side - or leaner than it used to be, whichever way you like to think about it. Fatten the LS a hair and you should be good to go - until it starts getting warmer out anyway.

I ordered a carb kit will see if that does the trick. Thank you for the replies gentlemen.

So the carb kit came and I started replacing items. I thought maybe it might be this stuff because the new spring was longer so for some reason I thought the old one might be wore out. However once I put it back together and back in the plane it would start and run fast then die when I reduced the throttle...and after it started once it just flooded out and would have to sit (then do the same thing).

Since it was getting tons of fuel and flooding I thought maybe the spring was too long. So I dug the old one out of a trash can with cigarettes and shiz in it then proceeded to lose it 30 seconds later so I ordered a Walbro carb. Ha ha

i cant believe atfer many many years of making gas engines they still cant get it from the factory