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Oct 16, 2017, 01:54 PM
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DLE 55 tuning difficulties... Wierd. Carb rebuild? New rings?


Hi everyone,

I have a DLE 55 in a Carl Goldberg Yak 54. I have had experience with DLE 30s in the past, but am having the hardest time getting this 55 to run well. Bought the engine used last year, unsure of history but was told it only had 2-3 gallons through it. Unsure what type of oil he used for initial break in, but I switched to Redline full synthetic and 22x10 prop, and have put 4-5 more gallons through myself. I have not been able to get this thing to run well (no where near as good as my DLE 30s), and have had several dead sticks... I am no stranger to gas engines and am familiar with the tuning process, but just cant get it. Here is what happens:

1)... If run at 1/2 throttle for a minute or so, engine will die (sounds like leaning out) when I advance to full throttle
2)... When run WOT for more than a few seconds, RPS will drop and it will begin to sputter
(I realize these two sound like symptoms of high speed needle running lean, but i tune it about 1/8 turn rich of peak on ground)...

3)... If throttle is "reved" when at idle, rpms will rev appropriately but then drop below the previous idle, sometimes causing it to die.
4... If allowed to idle for any length of time, throttle transition is poor (sounds like too rich)
5).. if allowed to idle for longer time (ie long final), will clog up poorly then die out.
(I realize these 3 sound like low speed is rich, but it is only about 1-1.25 turns out, and if leaned out any more the transition will lag...

Does anyone have any ideas on a good place to start? Carb rebuild? New rings (too bad bowman is no longer in business)? Or am I just missing something with the tuning? Any advice would be greatly appreciated!!!
Happy flying!

PS... reed valves seem to seat well. Running CM-6 spark plug.
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Oct 16, 2017, 02:14 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by Neb_16
Hi everyone,

I have a DLE 55 in a Carl Goldberg Yak 54. I have had experience with DLE 30s in the past, but am having the hardest time getting this 55 to run well. Bought the engine used last year, unsure of history but was told it only had 2-3 gallons through it. Unsure what type of oil he used for initial break in, but I switched to Redline full synthetic and 22x10 prop, and have put 4-5 more gallons through myself. I have not been able to get this thing to run well (no where near as good as my DLE 30s), and have had several dead sticks... I am no stranger to gas engines and am familiar with the tuning process, but just cant get it. Here is what happens:

1)... If run at 1/2 throttle for a minute or so, engine will die (sounds like leaning out) when I advance to full throttle
2)... When run WOT for more than a few seconds, RPS will drop and it will begin to sputter
(I realize these two sound like symptoms of high speed needle running lean, but i tune it about 1/8 turn rich of peak on ground)...

3)... If throttle is "reved" when at idle, rpms will rev appropriately but then drop below the previous idle, sometimes causing it to die.
4... If allowed to idle for any length of time, throttle transition is poor (sounds like too rich)
5).. if allowed to idle for longer time (ie long final), will clog up poorly then die out.
(I realize these 3 sound like low speed is rich, but it is only about 1-1.25 turns out, and if leaned out any more the transition will lag...

Does anyone have any ideas on a good place to start? Carb rebuild? New rings (too bad bowman is no longer in business)? Or am I just missing something with the tuning? Any advice would be greatly appreciated!!!
Happy flying!

PS... reed valves seem to seat well. Running CM-6 spark plug.
Sorry I don't know anything about a DLE55 however your post sounds really strange. It does not sit right with my logic. Maybe I am not too smart but here goes. No offense to you, I am just stating some ideas from what I read.

1) You bought the engine with 2 to 3 gallon already ran through it. You then run another 4 to 5 gallon of fuel through the engine. That should have taken quite a long time to accumulate so much fuel. Only now you are having issue with the engine?

Simply with those information I suspect your engine is getting old and has lots of carbon built up. It needs a good cleaning or maybe even a rebuild. Do you still have goo compression on the engine? Maybe you need to get a compression gauge and check it.

2) Sounds like your engine likes to die no matter which way you go. Both high speed, idle and transition. You need three good thing for an fuel burning engine to run properly. You need spark. I will check your ignition module. You may have a timing issue or the module is just getting tired from so many hours of vibration. Easy way to check that. Get a new ignition module and see what happens.

3) You need fuel. So your engine has been run for a while, you may have air leak or fuel feed problem with your carburetor and/or the engine itself. Forget about rebuilding your carburetor. That is a cheap way to bungle it up. Just buy a new carburetor and slap it on. If it is carburetor issue a new carburetor will certainly fix it. If you rebuild the carburetor and the symptoms persist you will always be suspicious of your rebuilding skills. Not saying you are bad in rebuilding but in general rebuilding a carburetor is not simple. Your gaskets maybe old and have been compressed for a long time. They will require a lot of patience to clean them off. Even after you clean them off, are you sure the metal surfaces are perfect for the new gaskets? Did that little scratch create a new leak?

4) We are now back to compression. Maybe your piston ring no longer moves freely on the piston. Too much carbon and it is stuck. So you get less then optimal compression. All sorts of issues come from that. How about your cylinder wall? After 8 gallons of fuel the wall may be scratched. How about loose bolts? Did vibration shook loose any of the engine bolts?

Lots to look at. The only way is to be patient and do one thing at a time.
Oct 16, 2017, 04:11 PM
Registered User
If it quits, it's lean or hot 99.99% of the time. From your note, it sounds like you may have a combination of the 2. You can eliminate overheating potential by running without your cowl.

If you'd like to try a different approach to the way you are used to tuning, you might track down the directions for the "tune the low speed first" method of tuning. I generally end up with about the same tune - but the process to get there is so foreign to this old man's methods it causes me to think differently?

Best of luck! -Al
Oct 16, 2017, 06:45 PM
Registered User
Thread OP
Hi there, thank you for your reply. The engine never really ran right since I bought it... the problem is not really getting worse, just remaining persistent despite my efforts. I will tear the engine down and see what I come up with. Would you recommend replacing the rings while i am at it? What is a good product you would recommend to clean the components?
Oct 16, 2017, 06:59 PM
Registered User
Replacing the ring decision would be made based on what I see on the tear down. I would not replace it just cuz.

I am NOT a big believer in all the internet hype revolving around custom rings and questionable need for reed massaging.

If you are completely frustrated with it, prior to replacing parts on a guess, maybe consider sending it out to ValleyView RC and have some very seasoned eyes have a look at it. They're good people with an awesome reputation.
Oct 16, 2017, 07:05 PM
AMA 46133
SeismicCWave's Avatar
>> I will tear the engine down and see what I come up with.<<

If you are mechanically inclined it definitely would not hurt to open it up and take a look. Feel between the cylinder wall and the area above the piston. Sometimes you can feel a ridge there reflecting a lot of wear on the cylinder wall.

>> Would you recommend replacing the rings while i am at it? <<

Sorry I cannot recommend anything without actually looking at the engine or the condition of the inside of the engine. That will be your call. Before taking it apart I would definitely do a compression test on it. At least you have a baseline.

Make sure you mark everything while taking it apart and don't do dumb things like I did. I put the piston in backwards once.

>>What is a good product you would recommend to clean the components?<<

Good question. I have been thinking about that myself. I am sure diesel and plain gasoline will work for cleaning some of the parts. I am contemplating about trying Hoppes gun solvent. I figured if the Hoppes solvent can clean the carbon off a rifle or pistol why can't it be used to clean carbon off our gasoline engines? I am curious if any one has tried it. I would love to hear feedback on this also.
Oct 16, 2017, 07:05 PM
Registered User
Thread OP
Yes, that is definitely becoming an increasing consideration. Have worked with them in the past - awesome group. My last effort may be to attempt to re-seal the crank case... There seems be gray sealant surrounding the crankcase connection... I don't believe that is a factory procedure, maybe that points to a rebuild from the previous owner? Either way. Also the engine leaks compression must faster when turning the correct way than when turning backwards... What does that mean?
Oct 16, 2017, 07:07 PM
AMA 46133
SeismicCWave's Avatar
>>Replacing the ring decision would be made based on what I see on the tear down. I would not replace it just cuz.

I am NOT a big believer in all the internet hype revolving around custom rings and questionable need for reed massaging. <<

My feeling is the same. Just because it is the latest trend and every one is doing something does not mean that it should be done. I like to keep things as simple as possible.

>>If you are completely frustrated with it, prior to replacing parts on a guess, maybe consider sending it out to ValleyView RC and have some very seasoned eyes have a look at it. They're good people with an awesome reputation.<<

If they offer such a service it would be the simplest answer.
Oct 16, 2017, 07:18 PM
Registered User
Thread OP
That an interesting thought about the gun solvent. I do have some laying around, ill give it a try and let you know how it works. Any thoughts on the bonded cases? It looks too sloppy to be factory DLE, so I am led to believe that the previous owner rebuilt the engine at some point... If I tear down, I assume yamabond will be acceptable to replace this seal...?
Oct 16, 2017, 07:23 PM
Registered User
Not much time on that engine / should not need rings under normal condition ... unless something is wrong / you could always check it out if not sure?

1) check fuel lines and clunks or filters to be sure no issues with fuel delivery.
2) Check ignition system for good solid spark / no loose wire connections, bad switches, or shorted wiring from rubbing, etc.
3) inspect carburetor thoroughly for debris, signs of moisture, and also defective diaphragm issues as well as proper adjustments in critical points as necessary
See this link for help on rebuild info:

https://search.aol.com/aol/video?q=w...mail-searchbox
Oct 16, 2017, 07:58 PM
Registered User
Thread OP
I removed the cylinder, and honestly seemed in better shape than I expected... No scratches, no carbon buildup, no apparent abnormalities. Piston and ring seemed appropriate as well. Still a bit concerned about the apparently aftermarket sealant between the cases (something the previous owner did not make me aware of), and the fact that is has significantly more compression when turned clockwise from the front (backwards) than counterclockwise. I am not sure what to make of that. I will give the carburetor a good cleaning / adjustment tomorrow and see if there is improvement.
Oct 16, 2017, 08:24 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by Neb_16
I removed the cylinder, and honestly seemed in better shape than I expected... No scratches, no carbon buildup, no apparent abnormalities. Piston and ring seemed appropriate as well. Still a bit concerned about the apparently aftermarket sealant between the cases (something the previous owner did not make me aware of), and the fact that is has significantly more compression when turned clockwise from the front (backwards) than counterclockwise. I am not sure what to make of that. I will give the carburetor a good cleaning / adjustment tomorrow and see if there is improvement.
I don't think factory will normally put on sealant. They generally machine the crank case faces to fairly good tolerances and the gasket will seal up well. If there is sealant that is a pretty indication there were some work done on the engine. Maybe that was the reason why the engine was for sale.

Sorry cannot tell you anything about higher compression while spinning backwards. Does the piston ring move freely in the cylinder groove? Since you have it apart maybe it is time to check the crankcase and the sealant issue.
Oct 16, 2017, 08:59 PM
Registered User
Thread OP
Yes, piston moves freely and well inside the groove. How do I go about evaluating the sealant issue? I don't even know what to do with it... Just try to re-seal?
Oct 16, 2017, 09:42 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by Neb_16
Yes, piston moves freely and well inside the groove. How do I go about evaluating the sealant issue? I don't even know what to do with it... Just try to re-seal?
Where is the sealant? Between the cylinder head and t he crank case or on the back plate? Did you remove the cylinder head? How are the mating surfaces? Flat and clean? Looks like there should be a gasket between the cylinder and the crank case. Clean the sealant off and check the mating surfaces carefully with a magnifying glass and a straight edge. See if they should mate without leaks. Get a set of new gaskets and put it back together. Not much you can do unless there is a definite issue like a crack or a gouge. Check the screw holes to make sure the threads are clean and not stripped. Make sure you torque the bolts when you put them back.

https://www.towerhobbies.com/cgi-bin...?&I=LXDKTA&P=Z

A new cylinder is $90 and a new crankcase is $75. If you find a problem it may be time to change them. Otherwise leave them alone.
Oct 17, 2017, 12:13 AM
Diesel Danny
danny mz's Avatar
Quote:
Originally Posted by SeismicCWave
>>>>>>>>>>>>> snip <<<<<<<<<<<<<<

Good question. I have been thinking about that myself. I am sure diesel and plain gasoline will work for cleaning some of the parts. I am contemplating about trying Hoppes gun solvent. I figured if the Hoppes solvent can clean the carbon off a rifle or pistol why can't it be used to clean carbon off our gasoline engines? I am curious if any one has tried it. I would love to hear feedback on this also.
Hoppes is made to dissolve copper fouling. It will not dissolve carbon (or lead for that matter).
If you do find something that can dissolve carbon the world would beat a path to your door and you would be a very rich chappie as goverments and greenoids would love you.

The way that a firearm is cleaned of these deposits is good old fashioned elbow grease and a stiff nylon or brass brush.

Given all that, the Hoppes solvent may be useful to remove baked on oil and other materials gumming up the works.

* Danny M *


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