el_xero

My Feedback: (2)

My first Gasser!!!!

So I've got a fairly new DLE 20 maybe going on two gallons through it so far and I've gotten it leaned out pretty decent. I'm running it at the required rpm according to the manual and using the recommended 16x6 prop..

It seems to be misfiring here and there and normally that would indicate to me that the engine needs a bit more leaning out, I'm flat out chicken to lean it out more, tempted really but I wanted to eliminate all possibilities so I decided to change the plug..

I've pulled it out and have had a look. I remember seeing a spark plug chart some place which tells you which color your plug should be but can't seem to locate the bugger now

(not sure which forum it was in and my search gave me so many possible forums. frankly, after looking though about ten for this cart I've decided I'd have better luck asking in here, besides I don't really trust my self to draw the correct conclusion anyway) ..

I figure id take a couple of pics and ask in here so if anyone can give me some incite that would be awesome?

What do you guys think? Am I too rich on this here? I'm guessing that this is a resounding yes?

ahicks

My Feedback: (2)

16x6 is too small a prop. It's not loading the engine properly, allowing it to turn way over the 8500rpm (or so) that's proven safe for keeping the rod inside the crankcase of this engine.

Increasing the load will help reduce the stuttering as well. You can prove this to yourself by paying attention to what it's doing in a climb. My bet is your issue disappears nearly immediately as soon as you start into a climb - which is obviously increasing the load.

You may want to try gaping the plug to .025" as well. This is a well known trick that very often results in a noticeable difference in stutter, if not making it disappear altogether.

You might be a hair rich, but leaving it that way will keep the engine reliable and friendly - with little concern for engine outs or being picky on it's needle settings. Leaning it will not likely increase your performance one bit, nor will it make the plug last any longer.

Truckracer

My Feedback: (19)

Are those two gallons of fuel burned on the ground or in the air?

Propworn

My Feedback: (3)

Is that the plug that comes with the engine. Others found swapping it out for a different plug helped how it runs. Hicks has given good advice try a little more load on the engine.

Dennis

el_xero

My Feedback: (2)

Thanks Guys, I'll have to go order a few larger props then, too bad though I've got a heap of 16x6's here, they are all I've got, ah well.
That plug is an NGK CM-6.
The fuel burn I mentioned was flight time very nearly two gallons.
I do spend a bit of time flying round half throttle and Idle to near idle in the air also, usually going wot when flying upwind.
Widening the gap? Hmmm. I guess I'll have to get filler gauges for that, wonder if I can get them locally.
I've also been told that my fuel mix might be the culprit... I started out on 30-1 recommended by the manual on regular oil (non synth)
and moved to 32-1 with klotz synth. I've gone through 1.5 liters of that already now and have a batch of 3.2 liters using up now.
I'm getting a bit of lack tacky gunk coming out my stinger too not loads and loads of it but it's there.
The engine is running somewhere around 8500 rpm indeed.. but I'd like to mention that even before I first started it I installed
one of those silencers similar to what troy built models sells to keep the noise down a bit. I don't know if that affects the tuning any.
I gotta run now I'll post a pic of it a bit later on it fits on the end of the stinger and is held in place with a bit of a silicone tube and some zip ties.

el_xero

My Feedback: (2)

Here is th link for the silencer which I spoke of.. this isn't the exact one, that I have though. I've got the hobby king knock-off which I doubt is that much different as it's just a hunk of metal with holes drilled through it.
http://www.troybuiltmodels.com/items...0SILENCER.html

ahicks

My Feedback: (2)

No experience with the silencer, but I can tell you that the black gunk will never disappear entirely, but will diminish noticeably as you get more time on the engine.

30-32:1 mix is fine. For breaking in or afterward.

Feeler gauge shouldn't be hard to find for 5.00 or so. Discount auto supply or any mass merchandiser should carry them.

av8tor1977

My Feedback: (6)

The plug coloring indicates that the mixture is fine; almost classic, if not just a tiny touch on the rich side which is ok. However, in the first picture I see some specks of what could be aluminum that bother me. You should check the timing carefully, and perhaps upgrade to premium, (high test) auto fuel. The engine might be detonating and the aluminum specks are from the piston. Definitely check that timing as that could be the cause of your stuttering as well, and install a fresh spark plug.

AV8TOR

el_xero

My Feedback: (2)

Ah cool. good to know that it will diminish some. I'll look around for a gauge, I'm not in the USA so might not be as easy to locate over here to be honest and def not so cheap haha.

el_xero

My Feedback: (2)

Hm I'll put in about an 8th of a turn again and see if it chances anything. I'm not so sure about the specs it could be a reflection of the over head lamp I was using (took the pics at night) I'll have a closer look later on.

Um how do I go about checking that timing? I have zero idea how to do that.. Like I'm completely lost here haha.
Should I pull the cylinder apart and have a look at the piston while I'm at it?

I don't think we have any special kind of fuel we can get over here. I'm pretty much stuck with whatever's at the pump over here

I do find that the engine guzzles gas quite a bit faster than anyone else is saying though so It could be rich that was my first guess and second was the
spark plug. hmm.

av8tor1977

My Feedback: (6)

The Chinese engines often have the timing set incorrectly and it is good to check it. Here is a good video on setting the timing:

https://www.youtube.com/watch?v=GBXFpxWg7vY

AV8TOR

dirtyoldman00

My Feedback: (100)

I would change the oil for my 2 cents lot of deposits that piston will coke up quick

Truckracer

My Feedback: (19)

I rarely comment on plug readings from photos because with just the photo, you never know how the engine was run before the plug was pulled. To make a correct reading you really need to hear (witness first hand) how the engine was run for a few runs before the plug was pulled. I'll stick my neck out this time though! I agree with av8tor regarding those specs on the insulator around the center electrode. More troubling though is the appearance of the oil residue on the threads. It almost appears burnt on as if the engine has been run too hot which could also contribute to the specs on the insulator. While oil on the threads is 100% normal, if run at normal temps it is just liquid where that oil is looking a bit stiff like it has been hot. If it were my engine I'd want to pull the jug and inspect the cylinder walls and piston crown and skirts. Looking at the piston crown from the bottom side would disclose in short order whether the engine has been overheated.

I would be curious to see some photos of the engine installation and cowl.

LarsL

My opinion is that you are too rich. As some others have stated, that is assuming you have run it "properly" before taking the plug out (loading it appropriately, not an excessive idle,etc.). I road raced 2-stroke motorcycles years ago and I was always looking for a rich golden brown color. Whitish was too lean and a no no headed for a holed piston. Blackish oily was too rich, safe but would be down on power.

i get a few plugs, warm the engine up on one, then put in a fresh one, do a 1-3 minute high speed run, shut it down, and pull/check it.

Lars

Steve S. Helland

My Feedback: (15)

Yep, slightly too rich. Lean it up just a tad...not much. Prop up to either a 17-6 or 16-8. This is my opinion.
Good Luck.

opjose

+10!!!

Yup, novices will hear the "popping" in the air and assume that the engine is out of tune.

I've seen guys fight with the settings for hours trying to eliminate the popping sounds they hear in the air.

I'll walk up loosen the timing screws, retard the timing a bit, retighten and the noise disappears.

av8tor1977

My Feedback: (6)

It's pretty tough to really tell the tune of a model airplane engine by reading the plug as is so common with motorcycles, etc. You have to do what we call a "clean cut". That's where you fly the airplane for about a minute at full throttle, (if that's possible with todays way overpowered planes), then kill the engine without idling it down. Yep, then you're stuck with a dead stick landing, so hopefully you are good at that. Then you can read the plug. Otherwise, when you idle down to land, taxi back in, etc., the plug color will not truly indicate what is happening at full throttle. Better to set the mixture with a tach on the ground, and then listen to it in flight to fine tune it.

But in your case, as TruckRacer says, it would be a good idea to have a look at the piston. Those specks of aluminum had to come from somewhere, and they are indicative of detonation. As for temperature indications, look for oil stains on the piston skirt, but more importantly look inside the piston at the underside of the piston dome. Some oil staining there is rather normal, but if you see any ash, you are running the engine dangerously hot and the engine will be "toast" shortly.....\

Then this gets into the realm of advanced mechanics, but if the timing is close to correct, the center metal electrode of the plug will have a thin line just below the tip that is deposit free. But check the timing in the conventional way regardless.

AV8TOR

the pope

el_xero

My Feedback: (2)

Wow thanks guys that's quite a bit of info on things to look into. Sorry for my tardy response I've not been able to get to this for a bout a week now. I'll look into the ones I can for now, the others will have to wait.
eg. I can't crap open the engine unless I have an other set of fresh gaskets and I can't take the cowl off to do timing adjustments because I'm going to need some more RTV I loaned mine out to a buddy (he's a bit far away from me I think I'll have to get a whole new tube) but for now I'm re-reading everything on here and seeing about what I can immediately take care of.
Def will check out the timing def will be changing up my oil to red line I hear it helps to clean things out some def will adjust my HS needle and I'll prob take off the silencer to do it right.. I'm getting a mini tach soon to help with that.

Oh and I don't think those specs are aluminum.. I took the pic at night under a lamp and I'm suspecting that what we're seeing is really a reflection of the lamp/camera flash. I'm looking at the plug in day light and I can't see specs. I'll be changing the plug also and looking at getting a filler gauge and adjusting the spacing a bit too..Thanks for the all your help guys i"ll be re reading this thread as I go and report back what I've found..
Thanks Pope for the chart!! I was looking for some thing like that, and to be honest I'm glad I didn't find it because coming here gave me a wealth of info I never expected to get just from asking in here!
You guys have been truly awesome with the help truly!!!
I'll report back soon as I get sorted out!! and I'll send those pics which were requested!

ahicks

My Feedback: (2)

Feeler gauge, not filler gauge. If you ask for a filler gauge at an auto supply they're going to look at you funny. -Al

el_xero

My Feedback: (2)

Hahah feeler right hahahaha good one! I'm going out flying today hopefully so I decided to try a few things out at home while I had some time.. just for testing I got one of the dle plugs *crap ones* and removed the silencer. Ran the engine and found that my high speed was around 9170rpm a bit above what is recomended (silencer off) I immediately remembered the prob being too small thing. Low speed was 1724rpm there about. I ran it high speed for a bit then shut down let the engine cool and checked the plug...it's a new plug so I did not expect to see any change in the plug and there wasn't. I put the silencer back on and ran it again and my rpm dropped to 83-8500rpm. Which is somewhere around it was sitting before and my low speed was close to 2000rpm.. so this silencer Def does something with the rpm. I remember my thinking back nlthen a bit clearer now, I never bothered leaning the engine up to 9000rpm because troybuilt models did say that the silencer robs you of some rpm at the top end. So I figured meh leave it there.. I suppose that could be the reason for my darker colored plug. Anyway I leaned it out a bit more just a little over an 8th to a quaternary turn and got it round 87-8800rpm now and 1770rpm on the low end....I ran it wot for a bit maybe close to a minute and then cut the ignition power when it cools I'll take pics of the plug...again I'm using the dle plug just for testing... I did hear a couple miss fires in between leaning out at wot.. but my last run I didn't hear it at all. It's only a short ground run and I know it's no substrate for flight but it's the best I can do for now...

I can't pull the crank case apart yet to have a look at the piston so in did the next best thing and shined light down the plug hole to have a look.. piston looks blackened and normal i suppose..I did that also when I first got it and saw some tiny circles from the center outward on the piston head. They are still there and don't appear to have any deterioration on the piston head as far as I can tell. I'll take a pic of the plug when the engine cools and post it later along with the new ngk plug after flying. Wish me luck

el_xero

My Feedback: (2)

So anyway. I'm guessing that the best way to tune this engine is with the silencer off then. Put the silencer back on after its tuned? I don't much about engines but I'm thinking that it's not a great idea to lean the engine out to full recomended rpm with the silencer on as you're supposed to loose about 3-400 rpm with it on anyway. I'm afraid I'll over lean the thing if I lean it out with the silencer on.. what so you guys think about that?

CK1

My Feedback: (60)

You need to tune the engine with the silencer in place that you plan on flying with.

Truckracer

My Feedback: (19)

+100! Tune the engine exactly the way you will be flying it. Why would you want to tune the engine then bolt something onto it that will change the whole tune of the engine? Also tune for max RPM with whatever prop you will be flying. If RPM is too high, you have too small a prop and likewise, too low RPM, too large of a prop. el_xero, you're making way too much work out of this tuning thing! Set the high speed, HS needle for peak RPM then back the HS needle out a tiny, tiny bit. You just want to make sure you are not lean from RPM setting. You just want to be very slightly rich from peak RPM. Set the LS needle as lean as you can set it where the engine will still be able to accelerate smoothly and without hesitation when you push the throttle to full. Other than knowing peak RPM, you really don't need a tach for any of these adjustments as your ear will tell you all you really need to know. We already know a 17-6 or 16-8 will work well for the prop size and you can experiment from there. These props will put you in the RPM range you need to be in. Good luck.

el_xero

My Feedback: (2)

Hmmmm alright I got it.. didn't get to fly today though so I'll run through that last suggestion tomorrow morning and report back thanks a bunch guys.