7kings

My Feedback: (1)

Hey guys. I'm experiencing some strange behavior with my DLE 55 powering my Pilot Yak that I hope someone can offer some insight for. Please excuse the length of the post, but I want to make sure that I'm as complete in my description as possible.

The engine has about 2.5 gallons through it, and I'm still using the break-in prop (Xoar 22x8). I'm using genuine NGK CM6 spark plugs in it, and only use filtered 93 octane gas from brand-name gas stations at a 30:1 mix with synthetic blend low-ash 2-stroke oil. I have clunk filters (screen-type) in both my filler can as well as my tank, and have a an inline fuel filter between the tank and the carb (I mention this just so everyone has the full story, not because I believe it's better or worse than how other folks run theirs). When I first installed the engine, it fired after a short amount of effort and proceeded to run fine. I put 15-20 flights on the plane without incident over the course of a few weekends, the engine running very well during this time.

Then one weekend I brought the Yak back out to the field and tried to start it, but had a VERYdifficult time getting it running. It would pop and start, but then die after a few seconds, or when I tried to transition it. A few of the folks at the field who are more experienced with gas engines than I am (this is my second one, the other being a DLE 30 that has never given me a problem right from the box) helped me check all the normal troubleshooting steps, and finally set to making some adjustments to the needles to try to get some results. After a bit, we were able to get it running pretty reliably and I flew it the rest of the weekend without incident.

The next weekend I brought it out and had similar issues, and again, a few folks helped troubleshoot and we ended up adjusting needles again. Once again, we got the engine running, but now it was so rich that it was developing very little power and never cleared out, even at WOT. Still, I flew it the rest of the day without further incident.

The next morning I came back out to the field and decided that I was unhappy with the extremely rich running (plus the expectation of impending fouled plugs, the inefficient break-in of the engine, and the threat of a dead-stick) and returned the needles to the factory settings. Voila! Immediately, the engine fired, ran great with a burble up to ~40% throttle, and a good clearing out, transition, and power production above that. The rest of the day was flawless, and I was exceptionally pleased.

That brings us to this weekend. I brought the plane out, filled it, choke on, ignition on, throttle at idle. 5-10 flips and the engine pops. Idle off and another few flips and the engine fires and idles for a few seconds before dying. Choke, flip, pop, choke off, flip, fire, run, die. Rinse and repeat. It really sounded like the engine was running out of gas, but we couldn't find any reason for it. There was fuel in the lines and there didn't appear to be any air leaks. I checked the fuel screen in the carb and made sure it was clear, and also swapped the spark plug for a new one just in case. We verified the needle settings and then richened the low by 1/8th. The engine still wouldn't idle, so I drained all the fuel out and filled it with fuel from another can, thinking that I may have a batch of bad fuel. Suddenly, the engine fired up and idled, but died when I tried to transition, so we richened the high speed needle and the engine was now running and transitioning, albeit rich on the high side.

I flew the plane around a bit, happy that it was running but unhappy at the power production at WOT. I had grown used to its usual power output, and this felt very sluggish (because we had the high speed needle very rich). I landed the plane and set both needles back to factory settings (AGAIN) and fired the plane up. It fired and ran perfectly (AGAIN). Low speed, high speed, transition, idle, wide-open throttle, the whole bit. The power was back to normal and the engine sounded GREAT.

Must be the fuel, right? Well, I figured the only way to be sure is to drain the fuel that was in the tank and put my fuel back in and see how it runs. So I did this and flipped the prop and the engine started right up. I sat there a few seconds, waiting for the engine to die, but it ran beautifully, transitioned great, and produced the normal power output that I had grown used to. I flew it for several more 15-minute flights to ensure that everything was good, and experienced no further issues.

So, once again, I've gone to the field with stock needle settings, experienced engine problems and made adjustments to just about everything we could think of to troubleshoot the issue, got the engine limping along, only to end up exactly where I started (stock needle settings and my own fuel) at the end of the day with an engine running like a top.

Jeez - at this point I have no idea what to even think. There seems to be some sort of weird voodoo going on and I'm thinking of checking the city archives to see if the flying field is built on an old indian burial ground or something. I'm hoping that someone has some idea of what might be going on.

Thanks all.

All Day Dan

My Feedback: (5)

It sounds like it's time to check the reeds, rebuild the carburetor and finally replace the sensor and ignition module. Dan.

7kings

My Feedback: (1)

Is that common? I don't even have 3 gallons through this engine yet. Would this cause the intermittant issues I'm seeing, or would that present more of a consistent failure?

ggraham500

My Feedback: (4)

Just for "grins", remove the inline filters and replace the fuel tank clunk so that there is no impediment in the fuel flow. See if that helps.

7kings

My Feedback: (1)

I actually added the inline filter after the first time I experienced an issue (forgot to mention that in the OP). I'll definitely take a look at the clunk in the tank, though. Maybe there's something floating in the tank that blocks it periodically...

BarracudaHockey

My Feedback: (11)

Well there's a few things I'd do off the bat.

Put a proper load prop on it and use regular unleaded fuel with 40:1 synthetic oil for starters.

I'd personally get rid of the inline filter as well.

Cyberwolf

My Feedback: (4)

First off I would check the tank and lines then ditch the inline filter, if all is well there then I would move to the reeds and lap the reed block flat and smooth, reassemble and run it and see if it made any difference, a lot of the reed blocks are not flat and don't seal very well. Do one thing at a time starting with the simple stuff and work up from there.
Also make sure the reeds are installed the correct way, they should have a slight arch to them the arch face's away from the reed block, so as you tighten the screws the reeds have some spring tension on them to help seal better.
And no this is not common to have this sort of issues with such a small amount of use.

All Day Dan

My Feedback: (5)

You've done everything else. Try these. Dan.

7kings

My Feedback: (1)

I have a 23x8 that I intended to install as soon as I had 3 gallons through the engine. I can throw that on sooner than later.

Question about the mix, though - DLE specifies a 30:1 ratio - is it generally accepted to deviate from this as the engine breaks in?

7kings

My Feedback: (1)

I think I will - seems like a few good things to try. Thanks!

w8ye

My Feedback: (16)

People run 30:1, 40:1, & 50:1 in the DLE 55 depending on the oil they use

BarracudaHockey

My Feedback: (11)

The manual is conservative, guys run them at 100:1 though I'd never personally do it.

The smaller engines are probably better off on a little more oil but a good air cooled oil like Red Line or Sthil HP ultra will work fine on a 30 or 55 at 40:1

pe reivers

There seems nothing wrong with either prop or fuel. The problem is in the carb, (maybe water drops in the fuel)
If there is debris floating inside the carb before your needles, that explains the behavior you are getting. Good one minute, crappy the next.
Give the carb a good rinse, and blow out fuel passages. Repeat a couple of times. If you have access to an ultrasonic cleaner, use it with a gasoline bath and a syringe to pull fuel through the needle jet passages while still under sonic waves. When done, enjoy the debris inside the cleaner tank and go fly.

7kings

My Feedback: (1)

The weird thing is that once we get the engine running, it always seems to run well from that point onward for the rest of the day, until the next time I bring the plane out to the field, that is.

OliverJacob

My Feedback: (12)

I have a somewhat similar problem with a Brilelli 46. The colder it is, the harder it is to start. I have to keep the choke halfway closed after it started to keep it running. After a minute or two I can leave the choke open and it runs fine.
And I can start it up after that without trouble for the day.

I didn't take the carb apart yet, but I am sure the problem is there.

P47Tbolt

My Feedback: (20)

To me it sounds like you have a air leak somewhere between the carb and engine depending on
the outside ambient air temp. what was the temp outside on all of the your flights?
was it cold one weekend then warmer the next weekend ?when it is cold outside the engine
will want more fuel so it will be a little lean compared to flying it on a hot day.
with an air leak you get more air pulled into the engine so therefore you have to richen it.
when the air leak seals up you will be to rich,therefore you have to lean it.
I would look at the carb/reed block gaskets.
I also remember something about taking the reed block and sanding the surfaces flat on the DLE 55.
Also if your piston ring has not seated completely yet,air temp changes can have an effect with that due to
the expansion and contraction of the different metals.A lot of DLE 55 users are putting the Frank Bowman rings
in and seeing a better idle and performance gain.

just some ideas/thoughts
hope this helps
Roy G

7kings

My Feedback: (1)

It has been getting progressively colder in the mornings as we meander through winter, but I'm not sure that I'm seeing a definite pattern of temperature vs performance. I can't completely discount it, though. As far as the rings fully seating, I've got about 2.5 gallons through the engine, so I'm not sure they're all the way broken in. That being said, it does seem like something has changed from the first several weekends of flight, but I don't know that our mild Florida winter weather can account for it.

Michel

Hi

Is youre fuel line anywhere nere a hgh heat source ?


Michel

7kings

My Feedback: (1)

Hi. No, it's a pretty clear run from the tank up through the engine box, through the firewall, and right into the carb. Nowhere near any heat source.

warbird addict

The DLE engines are low compression engines and designed for (87 octane!!), personally I use a 22x10 prop and use a 50 to 1 oil mixed at 40 to 1 on 87 octane only, what I mean is every 2 stroke oil has a designed ratio (ie) 100 to 1/ 50 to 1 / 32 to 1 etc, make sure you're not taking an oil designed for a 100 to 1 ratio and mixing it at lets say 32 to 1 thats a no no, I'm a big fan of being a tad heavy on oil thats why I use an oil designed for a 50 to 1 mix and run a 40 to 1 mixture or a 100 to 1 oil mixed at 80 to 1.
Get to heavy of a mix on the oil and you will have a bear of a time getting it started as you will have had some low rpm engine time on it before shutdown the last time you used it which will have loaded up the base of the motor with oil that did not burn completely.
When you do get it started again does it puke out some black goo on the bottom of the plane after the first flight of the Day? if so what I'm saying might be worth investigating as I kinda had the same problem in that I tried some new synthetic oil and mixed it at 40 to 1 like usual, come to find out it was designed to be mixed at 100 to 1, we about wore out the needles figuring that one out.

captinjohn

Try this just for kicks. Get some Puregas from a marina and mix a gallon of it with Pennzoil 2 strokeoil at (30-1) forair cooled engines. Run that for a while and let us know what happens.

7kings

My Feedback: (1)

The DLEmanual specifies 87-93 octane, and I'm staying within that envelope. I'm not aware that 2-cycle oil is actually engineered for a specific mix ratio (and most of the bottles I've picked up actually provide a list of how much gasoline to mix with the oil to attain multiple mixture ratios). It was my understanding that it is the equipment manufacturer that dictates the mix ratios, based on the amount of lubicity needed for a particular application. If this is incorrect, I'd love to read any information you might have on it (I'm always looking to learn as much as I can about our hobby!).

As far as whether I get black goo on the bottom of the plane after the first flight of the day: not that I have noticed. Of course, throughout the day, I'll get a light oily residue on surfaces downwind of the exhaust.

7kings

My Feedback: (1)

I'm not sure I'm familiar with Puregas - is that the alchohol-free gasoline, or am I thinking of something else?

warbird addict

Talk to the guy from valley view Rc he'll also tell you that anything above 87 octane could give you problems , read the label on your 2 stroke oil there you will find it's intended mix rate, I didn't believe it either but compare amsoil saber and amsoil dominator for example and read the labels not all 2 stroke oils are the same intended mix rates.
For example I just pulled out a jug of Husqvarna oil for my chainsaw and it clearly states 50/1 mix so what could I expect if I were to mix it at lets say 80 /1 ?
Just passing along something I picked up , it pays to read the label and stay within the tolerances of what you are working with and you can eliminate that as a potential problem
process of elimination, with probably a dozen or so DLE55's the only problem I've ever had similar to yours was due to a bad oil mix rate for the type of oil I was using, additionally higher octane fuel in a low compression engine as I'm told causes preignition of the fuel and a hotter running engine which also causes it's own set of tunability issues
I can't comment directly on that as I've always run 87 octane and stuck to a close margin on what the mix rate was on the label of whichever oil I'm using.
To date the only problem which really isn't a problem is when it's screaming hot and super humid then I might be inclined to lean out the high speed needle a tweak.

Muttdog

I would replace the ignition module with another one. DLE 30 was my first gasser. When I set up the plane and test run the engine it shut off on me and would not restart until I turned the ignition off and then back on. Didn't think anything of it as this was my first one and thought I screwed something up. I ran a tank on the ground after that and had a wonderful maiden day of flying. Then a week later after a successful flight in the morning, I had a dead stick 5 minutes into my flight. I recovered the plane in the field and turned off all switches. When I got it back it fired right up. We looked it over and found nothing so Idecided to fly again and sure enough 5 minutes into the flight it deadsticked again. This time I tried to start it again out in the field and it would not start. I also noticed that when I looked at the digital tach I have under the canopy that there was no RPM being registered when flipping it over like I noticed before. All I did was turn off the ignition and back on again and it fired right up. got it back and drained the fuel to go home but wanted to fire it up to run it dry. This time it failed almost immediately and same thing as before, no rpm registering on the tach until I turned off the switch and turned back on. In the end DLEsent me a new ignition module under warranty and I have now put over 3 gallons of fuel with zero problems. Even though the issues are not exactly the same, they were both intermittent. Many of the ideas posted are valid but most don't cause intermittent problems like you are describing. Usually fuel system issues or air leaks are always there and do not come and go like you describe . A faulty ignition module/switch/battery/opto kill etc could most certainly cause an intermittent failure and ignition issues can very easily be mistaken for tuning/fuel issues. You could change the pickup as mentioned already but in my experience it is rare to see a hall effect sensor fail intermittently. usually they work or they don't unless there is a mounting problem. If you have the option to try another ignition I would do that first.