Hi all from Italy ,
I'm new to the forum, and sure, i have a big problem with a DLE 35Ra.

I bought the engine i think 2 months ago from china..it's an original DLE with serial etc.. but it has a strange problem: when i flip the plane upside down and i keep it here for some time(seconds....) and then turn it back straight the engine suddendly die. The engine is tuned correctly, transition is smooth. Recently i read that this problem could be caused by some backpressure in the cowl or even a problem with the metering spring.

I'd exclude the first case beacause even if the plane is a Sukhoi 29 140 from sebart (round cowl) the problem persist with and without the cowl and nothing change.

The metering spring instead it's unknown...I tried today stretching the spring starting from 1mm until reaching 5+mm of difference but the only thing that changed was the carburation and maybe slightly the throttle response(yes I've retuned the engine at every changing of the spring).

Anywhay i've done even the reedblock mod but didn't change much..and the funniest thing is that i even changed the carb with another identic but new and obviously nothing changed slightly.
Everything seems okey.. fuel tank, tubes, spark plug etc...This engine is making me crazy..basically it's useless since the plane is made for 3d stuff and as soon as i flip inverted the engine lean out and then dies after came back straight.

Oh yes i forgot to say that i'm running a Menz 20x8 wooden

Any thought in how can i resolve that crappy problem?

You've tried a new carb. runs upright just fine, flip it inverted for "seconds" runs ok, flip it back over and it dies.

- What RPM are you at when this happens? if it's at idle, that might be normal for an engine that I am assuming isn't broken in yet. A lot of us use an idle up/down switch to prevent this from happening during aerobatic maneuvers. It does sound like a fuel delivery problem of some sort.
- Can switch to a Walbro Carb verses the DLE knock off
- I think your pluming is fine since your engine runs well. Is your vent line looped around the top of the tank?
- The diaphragm hole should be positioned away from direct airflow.
- Make sure you spark plug cap is on all the way (get an NGK CM-6 plug, not the DLE plug)

A lot of random information, but I'm thinking your idle just might be too low until it's broken in.
Hope this helps a bit

I think you are too lean.

I think you are too lean too. That engine would probably run better with a little lower pitch on that prop.---Smitty

Originally Posted by AKNick

You've tried a new carb. runs upright just fine, flip it inverted for "seconds" runs ok, flip it back over and it dies.

- What RPM are you at when this happens? if it's at idle, that might be normal for an engine that I am assuming isn't broken in yet. A lot of us use an idle up/down switch to prevent this from happening during aerobatic maneuvers. It does sound like a fuel delivery problem of some sort.
- Can switch to a Walbro Carb verses the DLE knock off
- I think your pluming is fine since your engine runs well. Is your vent line looped around the top of the tank?
- The diaphragm hole should be positioned away from direct airflow.
- Make sure you spark plug cap is on all the way (get an NGK CM-6 plug, not the DLE plug)

A lot of random information, but I'm thinking your idle just might be too low until it's broken in.
Hope this helps a bit

Hi,

-yes it happen at idle..
-the carb is already a walbro, so nothing to worry about
-plumbing is ok, but I don't have a loop on the vent line
-i've already tried to move the diaphragm cap away but nothing changed
-spark plug is currently a DLE, but I tried the ngk cm6 (from a friend) without real changes..

Sure the engine is not broken in 100% yet.. anywhay I noticed that with a higher idle (I think 2000+rpm) the engine stay alive but however you can hear the drop of rpm, but I can't really fly with a very high idle(2000+) because the plane literally "run" away. I might consider switching to a 20x6 to sustain a higher idle. What do you think?


For the others:
The problem subsist even if evidently rich.

I’ve been battling this engine for months and have tried everything recommended on every forum and I’ve read and re-read all of them. I’ve tried: New carb, reed block mod, stretch the spring, put spacer Under the spring, baffling, diaphragm vent mod, different fuel ratios, etc. The engine dies when the plane is inverted unless you have it so rich upright it’s a blubbery mess. How many planes have been lost due to this engine? And yet you see other guys saying “ it’s a great engine,” “you’re too lean” or “ there’s a problem with your tank plumbing” Must be some of these engines are ok and some have this problem. I don’t get it. I’m no pro but I’ve been running gassers of all sizes for 15 years. this just pisses me off, the amount of hours I’ve spent trying to get this pos to run right, fixing landing gear, regardless, I’m not giving up. If others say they’re great engines there must be a way to make this thing run the same upright and inverted. When tuned right to run inverted it’s great! Just can’t live with that ridiculous sound of a sputtering popping engine. Whew! Ok I just had to vent about this engine! Thanks for listening ��

Phil, sorry. I know what it's like to fight an engine sometimes. When I bought my DLE35 new in late 2013, I also bought Bowman rings (from Frank Bowman at the time) and installed them from the beginning. And I swapped out the plug for a real NGK CM6. It's been run on Redline 40:1 from the start. Tech Aero IBEC set at 5.1 volts for powering the ignition.

I am in the group that is very happy with the engine. It's currently in my EF Extra 78" and runs flawlessly in all orientations. The only thing I've noticed on mine is that it's easy to overprime the engine before the 1st cold start of the day. When I've made that mistake, it won't hand start and I sadly have to pull out the electric starter. Subsequent starts are usually a couple of flips with a chicken stick.

Originally Posted by Phil liebo

I’ve been battling this engine for months and have tried everything recommended on every forum and I’ve read and re-read all of them. I’ve tried: New carb, reed block mod, stretch the spring, put spacer Under the spring, baffling, diaphragm vent mod, different fuel ratios, etc. The engine dies when the plane is inverted unless you have it so rich upright it’s a blubbery mess. How many planes have been lost due to this engine? And yet you see other guys saying “ it’s a great engine,” “you’re too lean” or “ there’s a problem with your tank plumbing” Must be some of these engines are ok and some have this problem. I don’t get it. I’m no pro but I’ve been running gassers of all sizes for 15 years. this just pisses me off, the amount of hours I’ve spent trying to get this pos to run right, fixing landing gear, regardless, I’m not giving up. If others say they’re great engines there must be a way to make this thing run the same upright and inverted. When tuned right to run inverted it’s great! Just can’t live with that ridiculous sound of a sputtering popping engine. Whew! Ok I just had to vent about this engine! Thanks for listening ��

Have you tried an up idle switch yet?
Which carb diaphragm plate mod did you do? This old picture you have set up I would rotate the carb plate towards the side or back. Since you’ve plugged up the cowling ears this probably doesn’t matter.

A lot of guys remove the idle stop and just let the servo do that, otherwise you risk bottoming out.

Also, I’ve run the vent fuel tubing on the top of the tank. Not sure if it matters now, but see the picture. Dunno. Just a thought.

Since this is only happening inverted, and will run rich, it sounds like an fuel/air delivery issue. It’s leaning out inverted. Why. Idle too low? Ram air hitting the diaphragm at a different attitude? Fuel vent line siphoning fuel our inverted?

You say there’s a new carb in there. It must be something other than the carb internals unless it’s not tuned right. It sounds like you know what you’re doing. I’ve chased my tail so many times because of my improper tuning... I really feel your pain. Been there a few times. Don’t give up!!

I know you have tuned it and I’m not doubting your ability... but a flying buddy of mine had the same issue and it was on a new DLE 35 and the problem was a mix of not being good and broken in and the low end was lean.. I turned the low end about a 1/16 of a turn at a time until it cleared up.. it’s on an EF Edge.. we also got rid of the stock plug for a NGK CM6.. hope this helps

Originally Posted by AKNick

Have you tried an up idle switch yet?
Which carb diaphragm plate mod did you do? This old picture you have set up I would rotate the carb plate towards the side or back. Since you’ve plugged up the cowling ears this probably doesn’t matter.

A lot of guys remove the idle stop and just let the servo do that, otherwise you risk bottoming out.

Also, I’ve run the vent fuel tubing on the top of the tank. Not sure if it matters now, but see the picture. Dunno. Just a thought.

Since this is only happening inverted, and will run rich, it sounds like an fuel/air delivery issue. It’s leaning out inverted. Why. Idle too low? Ram air hitting the diaphragm at a different attitude? Fuel vent line siphoning fuel our inverted?

You say there’s a new carb in there. It must be something other than the carb internals unless it’s not tuned right. It sounds like you know what you’re doing. I’ve chased my tail so many times because of my improper tuning... I really feel your pain. Been there a few times. Don’t give up!!

Hey AK Nick! Wow, that’s so excellent. I’m looking at those pics and slowly realizing that looks familiar! Wait, that’s my plane! Haha. Nice! ( I haven’t had my coffee yet lol)
Since then, I’ve got a new carb and it has a red aluminum diaphragm cover with the vent hole in the side of the cover and facing toward the back. I’ve also moved my tank vent tubing to the top of gas tank. I haven’t tried removing the idle screw or used an idle up. Thanks for the encouragement.
I’m thinking it’s probably in the tuning, and this engine is so sensitive to slight adjustments. I’m just scared to lean it much because of all the dead sticks I’ve had when I try to lean it out. I am going to keep working with it. After I put the new carb on it ran great for a few flights and I thought I had finally gotten somewhere then boom, out of the blue, inverted, dead stick. Will possibly pull engine and put on another airframe till I get it sorted out. Thanks so much for your help!

Originally Posted by RCAddiction

Phil, sorry. I know what it's like to fight an engine sometimes. When I bought my DLE35 new in late 2013, I also bought Bowman rings (from Frank Bowman at the time) and installed them from the beginning. And I swapped out the plug for a real NGK CM6. It's been run on Redline 40:1 from the start. Tech Aero IBEC set at 5.1 volts for powering the ignition.

I am in the group that is very happy with the engine. It's currently in my EF Extra 78" and runs flawlessly in all orientations. The only thing I've noticed on mine is that it's easy to overprime the engine before the 1st cold start of the day. When I've made that mistake, it won't hand start and I sadly have to pull out the electric starter. Subsequent starts are usually a couple of flips with a chicken stick.

Thanks for the reply. I also put a Bowman ring in mine. It starts great. Usually pops within a couple flips with choke and starts with a couple flips with choke off. It runs really strong, if I could just get it to run the same upright as inverted I’d be happy as a clam! I’m going to try a couple things recommend on these forums that I haven’t tried yet. Opening up the spark plug gap and flying it without the cowl.

Originally Posted by 3DJP

I know you have tuned it and I’m not doubting your ability... but a flying buddy of mine had the same issue and it was on a new DLE 35 and the problem was a mix of not being good and broken in and the low end was lean.. I turned the low end about a 1/16 of a turn at a time until it cleared up.. it’s on an EF Edge.. we also got rid of the stock plug for a NGK CM6.. hope this helps

Ha! I AM doubting my ability 😉 I should have figured this out by now. I will persevere! Thanks for the help guys! I will continue to tune the engine to get a happy medium between the two orientations.

No problem Phil! I've put a plane on the shelf for a winter to try and figure out an issue (which I did), but it took lots of thought, perseverance, and encouragement. Does it die instantly? or does it audibly sound different than die? Some carbs can pool up if too rich and die when flopped around. Have you tried Terry's guide yet? It's easy to read over steps, or misinterpret them. Read each step carefully and follow it. Your idle screw may get in the way when adjusting your end points for a reliable idle - which is why folks remove it. If you use a high idle it will not tune right. Play with it till it's running well, let it sit for half hour to cool off and fire it up again. Don't overheat it with prolonged ground runs. A slightly rich engine should not die unless your idle is too low to begin with which is what I'm thinking your problem is. Retune that puppy from factory settings and follow the guide:
https://www.flyinggiants.com/forums/...3&postcount=34


I'm leaning towards a tuning issue paired with a low idle, it's not acting like a component failure. doubt it's a plug gap issue. Put in a Idle up/down switch. I bet it wont die when idling higher rpm in flight inverted.