Another possibility is you have the low end rich. Cold engines need more fuel to start and yours starts good cold. A warm engine does not require as much fuel to start and if you are flooding the engine with a rich low end then it will need a starter and full throttle to get going. Check the plug color, if black try leaning the low end a little and see if it gets better. DLE20 will need more precise adjustments then a DLE55.

My DLE's all need choke to start and even after sitting for 10 minutes will need choke to restart. Also right after they start if I give them any throttle at all they will die. I need to let them warm up for 30 seconds before they will begin to take throttle. I know when I'm close on the low end when my engines do not take throttle when first started.

So if your DLE20 revs up the second it starts when cold your low end is somewhat rich.

DLE's have been very good to me so I'm hoping you find the issue.

Ok, I reworked my tank, provided a floating pad for the gas tank (to reduce vibration), and replaced all lines with taigon. Motor started up cold and after a minute or two died and would not start. It was not running well so I think it's rich right now. We took apart the carb and cleaned it out but there was no smoking gun. Everything looked ok. I'm the belief that there's a leak somewhere. At least it's reproduceable.

Mine will do that on occasion. Last time out I fired it up and somebody came up to me and started asking about it before I got a chance to get the rpms up. It faded out and quit. I finished the conversation and tried to restart - and it wouldn't. I pulled the plug and let it sit for about 20 minutes watching others fly, something I've done other times after flooding it for one reason or another (like leaving the switch turned off...). Put the plug back in and it started on the first flip. It was way rich. That's mine though...

Iv seen these "carbs boil over", for about 3.00 u can get a little w shaped tool that makes sure the metering needle inside the carb is set at the right height, if the metering needle is not set right it makes it a pain to tune. If its to high the diaphram will hold it open and can flood the engine, if set to low it can cause it to run lean. A while back I had one that after it heated up and u shut it off u could see fuel coming out of the main jet in the carb from the fuel boiling. Other than that I'd try wat one other has said with brake clean spraying around while running to see if u can hear the engine change speed. Hope this helps.

So, I'm waiting for a new plug but I think I'm sending it back to Redwing. I voided the warranty (on the carb?) because I opened it up to check filters (which i think is silly) but I'm more interested in just getting it running good.

Actually because I voided my warranty by checking my Filter in the carb, which is BS, I think I'm going to just buy a new carb from Tower Hobbies for $35 because Redwing was going to Charge me 20-30 to look at it + shipping, and get it back in 2-3 weeks. If there are any issues I can just return it and use there service. Obviously I can still have a problem but at least I will have a backup.

Check the reed block for poor reed seating

Be sure to tell us what is found. As several have pointed out various things that could be the problem, It is of interest to those who have followed the thread to know the cause.

While there are some general characteristics of these gas engines such as choke until pop and then choke off until start when cold, I do see differing reactions after the first flight of the day. My Zenoah's usually require choking when restarting for subsequent flights. I've a JC-28 and an MLD-35 however that start the first flip on subsequent flights with no choking.

An engine with electronic ignition that requires a starter is not typical, whether cold, warm or hot.

Had a friend at the field start to have idle problems with his DLE. Found a loose screw on the butterfly allowing the butterfly valve to wiggle. He tightened it up using a little Loctite. Gave is 20 so minutes and then flew it. No more idle problems. It appears to be a great running engine.

There's a warning on most Locktite bottles that says "do not use on plastic". Loctite will deteriorate plastic parts, should use CA to hold screws in plastic.

The butterfly, shaft, and screw are all metal.

Interesting, you must have a different DLE-20 than I do then, on the 6 DLE-20's that I own the butterfly is fiberglass and the pyramid is plastic.

Maybe some confusion regarding subject at hand on one of our parts. I was thinking carb, sounds like you might be thinking reed block?

Yep, I was confused, I thought you were referring to the fiberglass reed as the "butterfly" and totally missed the carb butterfly..........

At the end of this season I had some trouble getting my DLE 20 to run smoothly. Over the winter I will ensure the reed valves are seating properly and replace the stock ring with one from Frank Bowman (ordered today). In the spring I'll start over.