I did a similar thing to drewbags, my break in procedure was:

1 - Put DL in airframe.
2 - Run one tanks through to make sure it wasnt going to stop.
3 - Fly aircraft.

My prop for 'break in' was a 23 x 8 mejzlik which is my normal flying prop, i think you guys are over complicating the matter of running in, get it in the air!

Cheers

W

a

I'd agree, the breakin procedure is being over complicated. The most common questions I get in PM and other threads regarding breakin of a gas engine is tuning and breakin.

My point is, install the thing, tune and prop it correctly, run the correct oil mixtures and go fly it, the difference in load during flight as well as the airflow will be the best thing you can do for the engine and how long it lasts.

So I ask this, has anyone taken temp readings throughout the 45 to 60 minutes of ground running? If so what were they? I'll bet they were pretty high near the end of the run and if not the engine was so rich the plug was probably close to being fouled (nice and black in color)

If you are relatively new to gassers, I would recommend mounting the engine on a test stand to familiarize yourself with the fuel system and needles. It will offer a safer, more straightforward setup to get used to how things work. Also, this provides an initial troubleshooting step already taken before mounting your setup into the plane. If, when you mount things into the plane you notice problems, it is easy to deduce what may be different as compared to your test stand setup. Again, I would only recommend this for those newer to gas engines...and even then, would only leave the engine mounted in this way long enough to familiarize yourself with how things work, and get the needles set appropriately. Beyond that, I see more of a chance for harming the engine on a test stand than I see helping it....especially in respect to the dissipation of of vibration, and cooling. If you are already familiar with gas engines for our hobby, run a good break-in oil, tune the carb correctly and fly it. The std 10-15 min flights with cool down in-between, varying the throttle and load, will offer very good heat cycling during the ring seating process.

Chad

What he said

You guys may be right but I was new to gassers. So I followed the instructions for the first 2 hours at 2500rpm. I don't know why that is in the instructions if your just suppose to go fly it. Then I called Bob at dlusa to find out what he thought. He said not to run it at the 4000rpm but the 2500rpm thing was fine but not needed. That was after I had already ground run it for the 2 hours. My motor runs strong maybe not as strong as some but I'm happy with 6950 on a xoar 22x8 after about 1 gallon at 30 to 1 lawn boy. Bob told me that when You go synthetic you should see about 300rpms more. I can't wait to see that.


What kind of differance did you guys see When you went synthetic? Alot or a little?

My buddie has a Berrelli 366 60cc, he's really thrilled this the performance, it's turning 6700 with a 23x8 NX Prop. My DL-50 turns 6800 with the same prop.

John

Do not know why DLUSA still states the 2 hour @2500RPM run as part of break-in in their website. 2500rpm run can not be simulated in the air!

Ever see or hear of somebody breaking in a chain saw, or even giving it special attention? Basically the same thing we are running in our planes

The new instructions say to run it an hour I think.

Jrjohn, When I bought my new snowmobile they dumped some oil in the tank to richen it up and told me to ride it like I was going to ride it everyday. Just don't drag race it all day. I think that the guys that say not to make this break in thing such a big deal are right run it a little and go fly it.

Agreed, I like to run it a little on the ground in the plane for one reason, to get it tuned properly so I don't have a dead stick. As far as breaking it in. I fly it the way I normally do from the first flight foreword. (just a different oil, and more of it)

John

No need too. Just fuel it, tune it and go fly it. Let it cool a bit between flights and go fly it again. Heat cycles are good during the breakin. You'll know when it's ready, just check your rpms every so often and most likely you will need to retune once or twice. Most engines gain a few hundred rpm, even without switching oil (from petrolium to synthetic)

I used to use strictly Pennzoil Aircooled oil with is petrolium based from day once, I jsut chaged the mix so it was easy to see it was the engine breaking in and not the oil. I then started using 100:1 Amzoil and the first DA50 I had needed a rebuild after 30 gallon as it was carboned up pretty good. Now I use Belray at 50:1 and my other DA50 has switched to this once I saw an rpm increase which was roughly 6 gallons on Pennzoil at 32:1. At first I was turing a 23x8 Mezjlik at 6850 and now I turn it at close to 7200 and the engine is completely spotless that last I looked inside it

I'm breaking in my DL50 the exact same way using the exact same oils and will be switching out to Belray shortly as I have already gained 200rpm with the 22x8 amd will get another 200 or so after switching to Belray so I'll need a bigger prop to kep the engine in it's torque range

Welcome back jrjohn, thought we lost you. have you seen aerobob.

I am using Pennzoil Aircooled at 40:1 after break in on DA50. Good high RPM (7200 with Menz 22X8) and no overheat. I do no like Amsoil at 100:1 either. Bad to DA50!

Back to the break-in subject. From common sense, the slow 1-2 hour 2500rpm run would provide a better base for in-air break-in. The problem is that its advantage is not quantifiable. And thus people tends to skip it.

Thanks Ed I'm busy building foamys for winter flying. Just shipped one down to Florida yesterday so I have something to fly over Christmas vacation. Been doing lots of fishing too


John

I have talked to hm recently...I had a bunch of pattern questions for him and as usual he did a fine job answering me

I used to be a certified outboard engine mechanic and those engines are some of the most harshest run engines I can think of. Most people who own a boat only know two throttle positions. Low idle or full throttle. Kind of like a lot of people that fly RC. Most of these engine manufacturerers recomend a brek-in procedure that specifies running more oil during break-in and not running extended periods at either idle or full throttle. They also recomend that you not run at any one throttle setting for any extended period of time. This is basically how I break-in any new engine no matter what it is on. Strap the engine to the plane run it on the ground long enough to get it adjusted right and then fly it. Just take it easy while flying and keep varying the throttle.

This is my first gas engine, so pardon a dumb question.

For fueling, can I just put a "T" between the carb and the fuel tank. There will be a lead off the "T" to a fuel dot.

Will I flood the carb fueling this way?

Matt

That is the normal way to set up the fuel line for a gasser. Just be sure and close your throttle before fueling. Also make sure the tee is gas proof and be sure and secure the tygon fuel line at all ends. That line with soften slightly with exposure to gas and loosen no matter how tight it feels when put on dry. Also make sure you have a "gas proof" stopper in your fuel tank. BTW The only "dumb" question is the one you forgot to ask! That's the one that usually causes the crashes.[&o]

I agree with the above post except for the closing the throttle. The throttle has nothing to with the fuel when the engine is not running because you are not getting any pulse from the engine to pump the gas through the carb, and all you are controling with the throttle is the butterfly.

That was included due to the fact that it is printed on most fuel dot installation instructions. I believe it is a precaution in case the fill line is kinked shut.

Contempo,

No such thing as a dumb question....Every gas engine we use in our models has a pump in it and the only time gas is allowed through the carb is when the pump is moving which happens only when the crankshft is moving be it by turning it over by hand or the engine is actually running. Now if the pump is bad then fuel can flow into the carb and engine but that is not that common but can happen when/if the pump diaphram wears out or cracks from being dry after sitting a very long time and if it gets to that point you will most likely never get the engine to start and if it does it will not run well or long at all

I don't think the possibility of flooding through the tee ever exists. In a normal engine I'm sure it's impossible however, as I stated, it is printed in the instructions for many fuel dots so new guys reading that and then coming here may get confused with the conflicting information. Personally, I always shut my throttle after running my fuel out so it's normally shut the next time I fill the tank. The simple fact of the matter is that the gas can run freely into the tank and not into the carb so, NO, you can't flood the engine that way.

Al,

I did have it happen to me on a Brison 3.2. It had a bad pump diaphram and only after the first start and while fueling it I would see drips coming from the carb while pumping the fuel in, thankfully the carb was pointed to the side so it would not flood it. I got home that day and took the pump side apart and found a tear in it which was keeping the needle off it's seat.

The really weird part was the engine ran very well for 4 flights that day and then on the 5th one it started to run really badbut I had noticed it dripping on the 2nd flight and thought "what the heck"