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DLE 35 RA issues

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Old 05-18-2017, 03:10 PM
  #1
Cyberwolf
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Default DLE 35 RA issues

Hi all
My son and I both have the 35 RA engines ,mine runs ok so far, His on the other hand has been an issue from the get go, it likes to gurgle between 1/4/-1/2 throttle which as a rule I can either tune out or in this case run a line from the Dia cover to the inside of the fuse to a pill bottle and the problems solved. Not in this case, so here is what all I have done so far, Ran the line, opened up the gap on the plug to .026 removed the spring from the plug cap as it was stopping the cap from seating correctly. Checked the opto kill, checked the on /off switch I have gave the carb a good tuning trying several different methods, non have seemed to work.
Also the engine will just die W/O any warning what so ever, its totaled one plane and did some fair damage to another one because of this.

Let me back up here a little when I said mine runs ok, yes it does gurgle some but so far has not died on me.
Anyway were going to bench run his engine for a few tanks and see if it may be just a tad tight, as a rule I don't bench run my gassers for more than a few ozs of gas on the ground while setting up the carbs and stick them in the air.
Watching of course what I do with them for the first gallon or so of gas.
Any help would be appreciated I can't stand an engine that's out of tune or sounds like it.
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Old 05-18-2017, 05:21 PM
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First things first, you should be running the NGK CM12 plug.
After that if its not running better come back and report on what's going on.

I have run 4 of these 35's on various planes with no issues so I might be able to help. I've done the diaphragm mod on two engines for a P-38 too. No pill bottle just thru to cooler air on the other side of the firewall.
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Old 05-18-2017, 07:01 PM
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Chris, I'm curious, I thought the NGK CM6 plug was the standard for DLE, or most other, gassers. I have a DLE 35RA I got from a fellow club member and it has a NGK CM6, but he was having some mid-range burble issues. (I have not run it yet,) You recommended a NGK CM12 plug, I've not heard this before, but I'm interested, why is this a better plug for the DLE 35RA than the CM6?

Bob Mc
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Old 05-18-2017, 07:39 PM
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Hi Nick Long time no talk,
Anyway I thought that was standard procedure in any DLE product to toss the plug and go with a NGK I'm with birddogs though, I have never heard of or seen a NKG-12 plug, I use the CM -6 in all my smaller gassers .
There is quite a thread on the 35 RA with the same issues that were having so if you got 4 of them to run W/O a hitch I would beat the door down knocking on wood "LOL".
FYI its not the cooler air that stops the engine from gurgling its the constant pressure that's maintained by placing the line on the cover. Some cowls develop quite a high pressure area inside the cowling and actually push the diaphragm down flooding the engine which causes the gurgle.
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Old 05-18-2017, 07:49 PM
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My bad CM 6 is right, CM12 is two times better! Lol

The burble issues you hear in flight is caused by the load on the prop. If you hear that when the prop unloads on the down leg of a loop it's because the reeds are fluttering. The intake velocity is not high enough so the reeds close.
Ive tested many props and found on the DLE 55RA that the Xoar 22x10 wood or carbon removes the burble. The performance is the best I've seen of all the combos I tried, Top Flite, Zinger, Master Airscrew, Xoar.

if your seeing a burble or hesitation when adding power then you need to tune the carb better. After some run time from new you have to adjust the low end too, not just the top end. Also each day the weather is different so from weekend to weekend you need to see how it runs and make any adjustments necessary.

Fuel: I run 92 octane non ethanol gas at 36:1 with Klotz Technoplate.
I have tried Bell, Honda, Stihl, Golden Spectro, and Cool Power. I went back to Klotz because they run great and don't leave much residue.
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Old 05-18-2017, 08:01 PM
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The purpose of the mod on the diaphragm cover is to give the diaphragm its own air supply. The cowl pressure can be from heat or high air pressure or both resulting in a stalled pump. So soldering a fitting to the cover and running a tube out to another air source is a solution.
Also if your engine is cowled and its kind of tight then you can add a baffle between the carb and the muffler to block the radiant heat from the muffler. I made two for the P-38 and the diaphragm mod just to cover those bases. Plus I added large aluminum velocity stacks to increase carb cooling. Inside the cowls I baffled the engines too. Fully scale tight cowls and the engines run at 168F at idle. This all worst case scenario stuff but it works.

Ive run one 35 in a Zero and one In a TF Stinson and both run great without baffling or any mods.
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Old 05-18-2017, 08:09 PM
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What prop are you running on the 35?
Which oil and gas?
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Old 05-18-2017, 08:37 PM
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they dont quit when they are too rich.. you are probably too rich on the low and overly lean on the high needle.. they interact more than most people think..
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Old 05-19-2017, 04:08 AM
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I don't get why people with a single cylinder 2 stroke engine, running a carb design essentially unchanged for over 50 years (or longer), get so worked up over burbling in the mid range. That's what they do when unloaded (as in cruise mode). If you pull the nose up to add a load when you hear that, the gurgling goes away immediately. It IS about the load on the engine!

I think most will find that eventually you just get used to the gurgling and leave the engine running on the rich side. It's not hurting a thing, and you'll be rewarded for putting up with that with an easy handling engine that will last a long time. If you try dialing gurgle out with leaner mixtures you might as well get used to the idea of dead stick landing practice, because that's WAY more likely to happen when an engine is set lean.

These are not fuel injected multi cylinder engines. Don't make the mistake of thinking you're going to get it to run like something like that.
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Old 05-19-2017, 07:17 AM
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Considering that i build alot of my engines from scratch i think i know how to tune a carb. You have changed props to change the load on the engine, which may or may not get rid of a burble but it does nothing for the pressure rise inside many cowlings especially round ones.
The yaks and such are the worst but with the simple tube off the dia cover to the inside of the fuse
solves the issue in most cases. I have done many an engine and used the same prop it was blurbling on and it ran perfect after the tube mod. Just so happens the 35 isnt one of them. Plus its takes quite a lot to stop a gasser in the air and this one just dies W/O any warning.
It almost reminds me of the DLE 30 i designed the new backplate and reed cage for.
Thank you all so far.
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Old 05-19-2017, 09:44 AM
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Cyberwolf, First thanks for all the info I've learned from you in years past so adding my comments here are a bit like trying to teach the teacher if you know what I mean!

From time to time, we all come across an engine that just leaves us stumped. Sounds like you've met yours with the 35. I know you've ruled out all the possible mechanical problems and that you have a sound engine from that standpoint so that really only leaves ignition and the carburetor as a possible cause. Ignitions have been a source of many problems with these (and many other) engines but most of the problems have been confined to the sensors that will misfire in any number of ways causing a host of problems. I'd replace that first and as always, I'd highly recommend the ones sold by RC Extreme Power. Other sensors work fine too but the ones sold by Milton at RCXP are know to be problem free .... at least so far. If that makes no difference, I'd substitute a new ignition box to see if that makes any difference. If still no luck, I'd start looking at the carb for issues. You probably have some known good carbs there so I'd probably start out by substituting a different carb just to see if the engine runs any differently. The carb doesn't have to be the exact one for the engine, just a similarly sized WT or clone. If that resolves the problem, considering their relatively low cost, I think I'd just buy a new carb for the engine. If a carb problem is confirmed, I suspect there may be some fod floating around in the fuel metering passages and trying to clean those areas out can be very frustrating. If the fod moves to the wrong location, it can cut off the fuel flow. Oh yes, I assumed you've already done all the normal carb internal checks such as screen, proper location and conditions checks of gaskets, diaphragms, metering needle lever height, etc.

I'll be curious to hear what you find. While our engines can all have their own personalities, most of mine run quite well as provided and I do expect good, reasonably smooth performance throughout the throttle range. A bit of gurgling is normal at certain power settings and in certain attitudes but it shouldn't be excessive. In a few cases, I've had to make modifications or substitute carbs to get that level of performance, but that is the exception to the rule. A few engines are nasty by design but the DLE 35 isn't usually one of them.
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Old 05-19-2017, 05:01 PM
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Just a pet peeve Cyberwolf, maybe combined with not enough coffee. Apologies for posting something like that, with full knowledge it wasn't going to help your issue one bit. Should have just kept my mouth shut. Best of luck figuring out what you have going on. -Al
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Old 05-19-2017, 10:37 PM
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Al no need to be sorry about anything.
the reason i dont like the burble is i know for a fact it dose not need to be there and still have an engine that runs great never dies andsounds solid through out.
Chris i read about the heat sheilds and thats going to be my next step, thank you for reminding me about it.
Truckracer your words are to kind, i have followed your posts and have gained so much usefull information its not funny.
your correct this is one of those engines that has my back up against the wall.
what gets me is mine runs good so far not any sign of a dead stick and the burble is tolorable after i added the vent line. In fact i think with a little more time on the engine i can tune it so its not there.
i dont have any onboard telemetry to see just how hot the two engines are getting but neither seem to be hot on landing, in fact we ran my sons engine W/O the cowling the last time when it died.
im still leaning its tight on the cylinder, or something is a little out of line.
i could tear it down and check it out but that is alot of extra work and time i shouldnt have to spend.
Anyway guys thank you all for your input on this.
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Old 05-20-2017, 09:03 AM
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Just curious but which plane or planes are both engines having a problem when installed?
Do these engines have issues on a test stand?
Im thinking the fuel tank or the ignition could be the problem but two of the same engine giving you issues is statistically not realistic from a production standpoint. So in my opinion there's something outside of the engines contributing to their failure to keep running normally.

Maybe go back to basics and look over the installations again. Could be something simple, you never know!

Last edited by Chris Nicastro; 05-20-2017 at 09:29 AM.
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Old 05-21-2017, 01:02 PM
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Ok, thanks first off to my dad "cyberwolf" for looking into this further for me, second, the engine has been in two different great planes Factors, first one bit the dust twenty foot off the deck because I was going back and forth doing pop tops "yes I know better with a new engine but wth!" And it landed flat on all the wheels, rebuildable, but thought we would bypass for now and just had another kit shipped asap. On the second plane it would die in a straight line of flight 1/2ish throttle, no cowl on the plane, once landed the engine was cool enough to grab for a few seconds, nothing out of the ordinary so temp seems good. This is also where the burble CW was talking about, so the prop load isn't the issue he was speaking of, they both do it no matter what and yes he can fine tune an engine to neat perfection that people have trave led across the states to have him tune and setup their engines, but any how the point is It is almost like I shut the ignition off, one flip it starts right back up and runs good, so after the cost of two of the Factors, 2nd one didn't deal with its wrestling match with a rock pile very well, but anyways, here are my thoughts, bad ignition? Fuel tank problem "I used the same tank from the first plane since it was it's first flight when it let gravity win", or the plug cap, which in my opinion does not fit correctly, so I'm left here pondering plumbing problems in the tank or my ignition is bad. We have a brand new carb that towers have to me for free, I'm going to have cyberwolf redo my reeds if he thinks it is needed, because I have seen issues with older DLE engine reeds, I'm also ordering a new bowman ring just because I can :-P , thanks everyone is there anything else outside of a heat shield I should consider? No more factors, I'm going with MX2 this time, the factors were fun, but a few issues from the last one's glide habit had made me weary. Thanks all!
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Last edited by WingNuT3D; 05-21-2017 at 01:08 PM.
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