Looks like the time has come for me to breakin my DLE 55 engine.
Look for advice on the proper mixture, procedure and needle settings to do corretly.
I already have the Lawnboy Ashleess, and i guess 32:1 would be the mixture to use for breakin ?

Thanks for sharing your experiences,
Gaurav

My experience is limited to the RCGF engines.  We followed the manufacturers recommendations.  The things to watch out are :

1.  Fuel to oil ratio... more oil for break-in.  It was 1:30 for break-in on the RCGF ones, and 1:40 after that (from what I remember).

2.  Recommended props for break in.

3.  Amount of tanks/fuel for break-in.  I do remember that compared to glow engines, gas engines took more tanks to settle in.  Even when the official "break-in" is over, the engines seemed to work better as more and more flights were done.

Thanks Anwar,
And what was the procedure followed ? Similar to glow ? ie heat cycle by running it full thorttle for a few seconds and then running it at idle and allowing it to cool ?

What about the needles, do they behave like glow counterparts ? How rich should the engine be at breakin ?

Not having someone experienced besides me is a drawback, but then this forum will surely help !
Thanks

Gauravag
      Gas engines are not supposed to be run rich or Carbon deposits will build up fast. Here is a link with a lot of good info and step by step procedure for tuning a walbro carb. Not sure if the DLE 55 has a walbro or an EMAS(?) carb but the basic procedure should work for all gas engines.
http://tech.flygsw.org/walbro_tuneup.htm
hope this helps.   

Hi Gaurav,

Never try to break-in your Gas engine on ground, Just tune your engine, set your throttle EPA on ground that all. Set your Highend needle 1/8 in. rich side. Dont pull vertical or try to hover till your 9 lts. of Ashless fuel ends. Break-in prop 22x8. I have used & tune about 5 DLE 50 & 55 for my friendz.

Regards,
Harveer.

Some of my Pix....Njoy

Quote from: Harveer on October 18, 2010, 11:42:44 PM
Never try to break-in your Gas engine on ground

Can you provide some detail on why ?  We noticed that gas engines are harder to tune initially, so the chances for dead sticks are higher, if one starts flying on the first tank itself. May be it is just an issue of gaining enough experience.

Gas engines runs at high temp. if they run on ground. where, there is no relative air/wind for cooling & the temp of the engine goes up & it reduce the span of your engine. 100s of flights with "0" dead stick experience.

Sure.. once the initial tuning is done, they tend to run very well, especially after the first couple of gallons.  But flying the very first tank seems risky ?

But Anwar, some people also suggest breaking in a glow engine (After the 1st tank or so) mounted on the model 'In Air'. It is said that the air passing over the fins cools the engine and break in is smoother for the engine, keping in mind to as not to run it at full throttle for more than a few seconds.
Gas engines need to be broken in air for the engine to stay cool.
Actually I have absolutely no first hand experience in breaking in either a glow or a gas engine. All I write is what I've read up on how to break in an engine.
Comments from all the "Engine Breakers" awaited 

We just let it run on the ground for the first tank, at 1/3rd throttle for the first 40% of the tank, and about 60% throttle for the rest (with some slow downs in between).  Air cooling is an issue when you let the engine get too hot.

I do see that people do the break-in for gas engines in the air for the first tank itself, not for the added cooling as the main reason, it seems.  They are doing it because they can, and some manufacturers suggest that.  Zenoah manual says no break-in is needed, just take it easy a bit initially in terms of a rich needle setting.  This is because the true break-in of these engines happen over large number of runs/tanks.  I read in one case where they compare to chainsaw engines, where you just start cutting trees from the get go itself ! 

If you leave the cowl off its ok to run the a tank or two on the ground - to get the high end and low end needles set. When running on the ground always make sure that the engine is not "hard mounted" so that vibrations dont damage it. Its best to run it on the model with the wings attached. They act as great big vibration dampers!
Also I would suggest you check the timing becuse many chinese gas engines dont have the timing well adjusted from the factory - leading to rough running and vibration.  (for rcexl ignition the timing is 28 - 30 degrees BTDC).
But since gas engine do take quite a few gallons to break in properly this as Harveer has said, is best done in the air.
And while a gas engine can be run a little rich for ease of starting etc. it is not absolutely necessary as in glow, because it is ringed, and the con rod has needle bearings and is not bushed as in glow engines.
Another often neglected point is in-cowl baffling - it is important for the life of the engine precisely because gas as opposed to glow engines run much hotter.     

Anwar, cooling is critical in gas engine -even in chainsaw engines, because it runs hotter in relation to glow - because methanol evaporates at a much higher rate than gasoline -taking heat away in a glow engine.  However in a fully enclosed chainsaw engine the cooling is very carefully engineered -and it is the fins on the magneto rotor that provides the airflow over the engine.     

Quote from: flatspin_king on October 19, 2010, 01:49:52 AM
If you leave the cowl off its ok to run the a tank or two on the ground - to get the high end and low end needles set.

Exactly what I was trying to say !  Only the first tank (in our case, and it took close to 45 minutes), possibly a second.  We had the engine quit multiple times initially on the earlier part of first tank, and the needles needed multiple adjustments.  Under such circumstances, the first tank (or until you feel confident about the initial needle settings, whether it is a tank or two, or part of tank), seems best run on the ground.

Yes, we did it without the cowl on, plus the prop pushing the air back would provide enough airflow anyways.

Yes, We all ways tune the engine w/o the cowl yar....I dont thing the needle setting on these gassers r difficult if your fuel is ok (fresh) & yes, if u r going to fly a 50cc or so, u set the engine untill u satisfy. then it can take 1 or 2 tanks doesnt matters but it will definitely reduce engine life.

Hello All,
This is what I do and have seen people doing all over the world on the DA's and the 3W's, but basic principle is the same. First off the Prop needs to be a wooden, preferably a 22 X 8. Since this is a 55 cc engine you can use a 23 x 8 also. This will prevent your engine to over stress and over heat . Run - in with no cowl with Lawn Boy Ashless 32 : 1 fuel mixture for the ground run, for inflight u may put the cowl.

Make sure you do not touch the needles until you really feel its required. I do not touch my engine's needle's till I am really facing unwanted engine shut downs. I would suggest you run-in the engine one tank on the ground with RPM's in between 2000 - 3000 only, may be lower if possible.

After half tank check for full RPM and transition along with reliable Idle. Don't run after perfection in the first few flights, make sure and run after your engine running reliably and consistently. Hope this helps.

Thanks and regards

Toucan     

Thanks Toucan, Harveer, Flatspin and Anwar.
What do you suggest for the ignition battery pack. NiMH ?
Also, would you suggest using a choke servo ? Harveer, I liked your choke linkage, but wouldnt it be risky to operate, since the pushrod is towards the front ?

-Gaurav

4.8 v high capacity NiMh (eg. 2000 mAh or more)  battery is the simplest and best option in my opinion. The main thing to keep in mind that for the RCEXL ignition on the DLE the voltage should not exceed 6V otherwise it could damage your ignition or shorten its life. Since most 6V packs are much higher i.e. 7+ V when fully charged its best to stick with 4.8V, unless of course you use a regulator.       
As for choke servo its a matter of personal preference -I always prefer setting up a manual choke wherever possible - its simple and you save some weight. 

Well I agree to Flat Spin. You can go for any 4.8v NIMH or Nicd for the ignition with 200o mah battery pack. You should use a HD switch for powering the setup. For the choke servo I prefer the servo for redundant setup if the space allows. Weight increment is negligible. For a manual setup you may have to build in a block over which you will have to put a small bellcrank assly.

I believe a mini servo should be ample for the choke ?

A mini servo will burn off with the vibration and load Would suggest a Standard 3001 servo.

Weight increment is negligible.   Sorry

you save some weight.  

In my view, cut weight as much as posible. If u do neglect these points, it cost u a lot....  

Harveer,
I get it. Will save some weight, and not use a servo for choke. Will do it manual like yours.

Back to the ignitiion power source. I do not have a Nicad/Nimh 4.8 . Would it be safe to use a Life with a diode power regulator (Align one from heli) ? It has 2 diodes in series, and a fully charged Life gives 6.25 volts with it. Without it the voltage is 6.8V

Would this be a safe setup to use ?

I was going through the DLE manual and it suggested a 2 hour breakin on ground.
http://www.dlusa.net/Manual.html

However, you all mentioned that such a long breakin on ground is not needed ?

One more quick question - IS it safe to fly a the Yak without the cowl ? I am thinking I will keep the first flights without the cowl. The big frontal area has me worried though.