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RE: Dle-20 Blew up.... - 11/10/2012 7:40 AM   
DL826


 

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Besides,i am a representative of the DLE manufacturer ,and this is my first time to come here.

If you have any question,please feel free to ask me.

Thanks for your attention and support about DLE.

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RE: Dle-20 Blew up.... - 11/10/2012 11:29 AM   
SkyPilot101


 

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quote:

ORIGINAL: Truckracer


quote:

ORIGINAL: SkyPilot101

I suspect the problem lies in improper heat treatment by the manufacturer, or to be more specific, improper ''nesting'' of the crank shafts in the heat treat furnace. Most of the parts come out within spec, while a few others end up with inferior metalergy......It's a crap shoot, some are bad, most are good.

The 20 uses a pressed in crank pin so the crankshaft as a whole is not the problem. I would remind those quick to point fingers that DA had a similar problem with their ever so famous DA50 a few years back. They replaced the bad parts and that problem is now gone as far as I know.


Yea, it's pressed in, but also too hard & brittle, hence the reports of it shearing off.....In the materials industry, itis a well known fact that Chineese metalurgy is not up to spec.....Yet

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RE: Dle-20 Blew up.... - 11/10/2012 1:10 PM   
ahicks


 

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Status: offline 		My understanding is that they are not shearing off, but rather working themselves out? Could be wrong though...

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RE: Dle-20 Blew up.... - 11/10/2012 2:15 PM   
757jonp


 

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Status: offline 		Sure enough, I managed to shear mine off too. Not complaining really because I've been beating it up pretty good on a profile. No serious damage to the rest of the engine as it broke while idling! Bearing and pin had no discoloration at all, but I did observe that the pin was galled somewhat. Almost looks like the pin is to soft to me resulting in wear, then increased clearance, then continued use pounds it until it breaks.

Anyway, I replaced the crank and we're back at it. I've got another spare crank at a machinist right now where we plane to make up some spare pins, properly heat treated of course.

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RE: Dle-20 Blew up.... - 11/10/2012 3:32 PM   
BlackPowder


 

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Status: offline 		My friend was using a 16 x 8 xoar prop and yes it did shear, there was no sigh of galling or heat discoloring. He was running pump gas 40:1 mix and was on the 5th gallon. But we thought that it back fired and than it broke, but can't say for sure that it did backfire, thats why I started to read this forum. Thanks for the response.

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RE: Dle-20 Blew up.... - 11/10/2012 3:50 PM   
w8ye



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Status: offline 		It probably made a noise like a backfire when the rod slammed around inside as the pin broke?

The DLE 20 is worse about the pin breaking than the other DLE engines.

I would use more oil on the DLE 20 than on the bigger DLE engines.


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RE: Dle-20 Blew up.... - 11/10/2012 4:13 PM   
BlackPowder


 

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Status: offline 		W8YE & 757jonp,
Have either of you played with the timing on this engine? I am going to check my new 20 that has not be run yet. I have always set my other brand engines at 28 degrees here at 5,000 ft. But as my bigger DLE's have never given me problems I have never messed with them, just wondering.

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RE: Dle-20 Blew up.... - 11/10/2012 4:55 PM   
RCVFR


 

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quote:

ORIGINAL: BlackPowder

My friend was using a 16 x 8 xoar prop and yes it did shear, there was no sigh of galling or heat discoloring. He was running pump gas 40:1 mix and was on the 5th gallon. But we thought that it back fired and than it broke, but can't say for sure that it did backfire, thats why I started to read this forum. Thanks for the response.


I think you have found your answer.



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RE: Dle-20 Blew up.... - 11/10/2012 5:15 PM   
larryak


 

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Status: offline 		Saw the same thing happen to a friend of mine on THE FIRST START HUMMMMMMMMM.

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RE: Dle-20 Blew up.... - 11/10/2012 10:38 PM   
predman


 

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Status: offline 		Always 32.1 and never a problem. I know flyers who insist on 40.1 and have seen their engines in "repair status" I have not had any of my engines go south in over 2 years. I have the 55, 30, and the 20.

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RE: Dle-20 Blew up.... - 11/10/2012 10:58 PM   
K-Bob


 

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quote:

ORIGINAL: Truckracer


quote:

ORIGINAL: SkyPilot101

I suspect the problem lies in improper heat treatment by the manufacturer, or to be more specific, improper ''nesting'' of the crank shafts in the heat treat furnace. Most of the parts come out within spec, while a few others end up with inferior metalergy......It's a crap shoot, some are bad, most are good.

The 20 uses a pressed in crank pin so the crankshaft as a whole is not the problem. I would remind those quick to point fingers that DA had a similar problem with their ever so famous DA50 a few years back. They replaced the bad parts and that problem is now gone as far as I know.

Almost correct. They had some inferior parts supplied by a third party. The big difference is that they recognized the problem, admitted the problem, and took extrodinary steps to correct it, free of charge to the end user. Wayyy different than the CS, or the complete lack of CS, from China. They may correct problems eventually, but it will be inder the table and you will have to buy the next version engine to get it.



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RE: Dle-20 Blew up.... - 11/10/2012 11:03 PM   
757jonp


 

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Status: offline 		blackpowder- No, I haven't checked it yet, but I am curious about it. If it was set to early, I could see how that might lead to possible detonation and excessive loads on the internals. I'll get back to you on what I find.

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RE: Dle-20 Blew up.... - 11/10/2012 11:06 PM   
RiverLarry


 

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Status: offline 		I guess if is stats 32 : 1   then you need to use    32 : 1    it not that hard !!!!     why cant people under stand       32 : 1    is  32 : 1     crist !!!

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RE: Dle-20 Blew up.... - 11/11/2012 12:23 AM   
karolh


 

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Karol

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RE: Dle-20 Blew up.... - 11/11/2012 2:51 AM   
Daniel Spurlock


 

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Status: offline 		Thats why its DLE and not DA.i would say faulty material or machining.

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RE: Dle-20 Blew up.... - 11/11/2012 2:53 AM   
BlackPowder


 

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Status: offline 		757jonp,
I just checked the timing and just like Turd posted earlier in the forum mine was set at 38 degrees, but there is a lot of play at top dead center, so I moved the pickup as much a I could and now it seems to spark at about 30 degrees. Would be curious as to what yours is set at.

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RE: Dle-20 Blew up.... - 11/11/2012 4:10 AM   
w8ye



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quote:

ORIGINAL: BlackPowder

757jonp,
I just checked the timing and just like Turd posted earlier in the forum mine was set at 38 degrees, but there is a lot of play at top dead center, so I moved the pickup as much a I could and now it seems to spark at about 30 degrees. Would be curious as to what yours is set at.


If the sensor is mounted on the casting seam there is no way the timing could actually be on 38 degrees before top dead center. The engine would not run correctly at 38 degrees. There would be popping and other erratic behaviour if it would run at all?

When you are checking timing, you must turn the crankshaft in the direction that the engine runs!!!

The reason for this is that the ignition fires as the magnetic field of the magnet leaves the sensor. If you turn the crankshaft the wrong direction, you reading is off the width of the sensor.

With the sensor at the casting seam, the timing should be in the 32-34 degree range. They probably run better with the timing at 28 degrees if the truth is known?


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RE: Dle-20 Blew up.... - 11/11/2012 3:44 PM   
dreamwever


 

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Status: offline 		Oil try looking at  [ aeroshell oil sport 2 aviation oil ] very good stuff

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RE: Dle-20 Blew up.... - 11/11/2012 3:57 PM   
FuzzyDice


 

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Status: offline 		 I have been operating two stroke engines for 50 years . Remember the two stroke lawn mowers with a pull rope start ? We
were extremely rough on those engines .  If the DLE'S are that sensitive to a 30-1 gas oil mix it is because of their poor metallurgy.
What do you expect from a $300.00 engine . It takes $125.00 bucks to fill my truck. Order a new Chinese engine and hope for the
best ......OR buy a BETTER engine. :-) Dr. Festerpus says more oil boys !


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RE: Dle-20 Blew up.... - 11/11/2012 4:02 PM   
BlackPowder


 

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Status: offline 		On all the engines I have worked on the sensor is allways mounted on the main part of the engine. And yes is did spark at 38 degrees. This is not the first engine that I have timed, this is a forum for possible problems with this engine, as the title states DLE 20cc blew up.

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RE: Dle-20 Blew up.... - 11/11/2012 4:07 PM   
Speedy-Gonzales


 

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Status: offline 		I'm just throwing my 2 cents in here. I have a background in metallurgy and strength of materials. If you have a 10X eye loupe look at the face of the fractured ends of the pin. If it is dark on the face of the fracture and a clean break I would tend to point my finger to the fact that the failure was to a pre-existing microscopic fracture ( crack ) from the manufacturer. If the pin is hardened, microscopic fractures usually occur during the quencing process. Especially if the quench is a violent oil or water type quench. Air hardened steels are usually more stable but are intended for higher strength applications which do not make them appropriate for objects that have to bare side loads such as a crank pin.

If the face/surface of the fractured pin is "fresh" and there appears to be a lot of distortion when trying to mate the broken edges then I would consider work hardening or simply inferior materials.

Steel that is "unstable" is usually compromised during the heat treat and quenching processes. The "draw" usually defines the final hardness but rarely has much bearing on the microscopic transformation of steel unless the final draw is above 1200F.

Since the crank and crankpin are two seperate parts and only the pin has failed then it would be interesting to know exactly what type of alloy steel is used for the pin and what the hardening process is. A Rockwell "C" scale hardness of Rc 38-42 ( which is a very broad margain ) would be sufficient.

The 38 degree timing BTDC would put excessive loads on the whole rotating assembly. IMHO 30-28 degrees BTDC would be more in the normal range of operation.

One last thing!
The mangled condition of the lower rod bearing is very suspicious which leads me to believe the pin failure was happening over a longer period of run time rather than a sudden failure. Work hardening,distortion,and failure.

These are just my observations. I may be wrong and I may be right. Sometimes there is more to be learned from one's mistakes.

"I am not an expert but I did stay at a Holiday Inn Express last night!"



< Message edited by Speedy-Gonzales -- 11/11/2012 7:22 PM >

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RE: Dle-20 Blew up.... - 11/11/2012 4:34 PM   
BlackPowder


 

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Status: offline 		Thanks speedy,
I will ask my friend for the pin and look at it. He is going to rebuild that engine, parts are on order. Your 2 cents will be interesting.

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RE: Dle-20 Blew up.... - 11/11/2012 4:52 PM   
Speedy-Gonzales


 

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Status: offline 		Small parts like the wee itty bitty crank pin are usually heat treated in batch lots and the consistency of hardness is all over the place. You may have just gotten one of the bad ones. In a controlled H/T process the parts are usually QC'd and the bad ones are discarded.

If the QC process is less than 100% then many may/will make it into assembly.

Uhhhhhh.....poor QC ??

< Message edited by Speedy-Gonzales -- 11/11/2012 5:56 PM >

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RE: Dle-20 Blew up.... - 11/11/2012 5:28 PM   
SkyPilot101


 

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RE: Dle-20 Blew up.... - 11/11/2012 7:01 PM   
TimBle


 

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Status: offline 		Even with excellent QC processes, substandard parts can filter through. A total QC systems takes in-market performance into account as well which DLE appears to do.

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