How long should I run my DLE-55 without the cowling for break in? Just the first couple flights or several gallons?

Will fuel with ethanol hurt my engine?

Any advantages to using high octane fuel or will 87 do the trick?

Do what it says in the instructions and your engine will be just fine.

You can forget about old glow engine style break-ins when running a gasoline fueled engine initially. While methyl alcohol has little to no lubricity, gasoline has quite a bit, making the initial runs less critical. Just like any other internal combustion engine, do not run it way to lean. A couple hundred rpm (yes - hundred - not thousand) less than peak on the rich side will do the job just fine. If the cowl has been set up properly for a gas engine, there is no real advantage to running the engine without the cowl during flight.


Ed Cregger

Use regular gas with or without ethanol

Sounds good to me. Pretty much what this guy says is correct. The BS that was going around about using Lawn Girl is H.S. Use a good 2 cycle oil, run it just a little on the rich side. All your doing is trying to seat the ring properly.

I've never broke in a gas engine, just fly it.............

An engine guru told me if you turned a new gas engine over the compression just once, it is broke in. Just gas it and go!

In the instructions it says to run without a cowl...where? Have you read the instructions?

As for Meschmidt's guru. I was wondering where that villiage idiot got off to. I see Meschmidt found him as an engine guru.

Whew! I'm glad I didn't say that...


Ed Cregger

My 2 cents....have the oil ratio a little rich...not the hi-speed needle. It is your choise also on cowl. Having it off you can check the bolts on everthing easy, and when satisfied,...place cowl on.It is good to re-check mounting bolts ect after thefirstcouple of flights. Always have a line from pump cover into dead air in fuse. Capt,n

On Toni Clark's site it talks about cowl on and off.....from what I gathered, the engine should be broken in (in the air) as it shall spend its life-cowled and baffeled appropriately.

That's how I roll, the same as the Capn'!
I like to check the bolts after each flight for the first several. Plus if it's a new plane and you smoke it into the ground on the maiden, you could always sell somebody the NIB cowl.

Understand, but how else can I be true to my signature line I'll go so far as to note you didn't disagree with it.

1) Fly with the cowl on but make sure you have good airflow over the cylinders. Also, leaving the cowl on doesn't mess up your CG.
2) About 10% ethanol, it varies by state, is in gas. From what I read, most gas engines now days have diaphrams in the pump made of rubber that resists ethanol.
3) I use 87 octane, 10% ethanol gas mixture and a 8oz of Lawn Boy oil at 32:1 for two gallons for break-in. I will switch to a generic two stroke weed eater oil I got from Ace, should be ok. Reason you want to use two stroke oil is because it has additives that help the engine. Outboard boat motor oil doesn't have those additives (that air cooled two strokes need) because boat engines don't need them as they run steady rpm and temperature.

Also, during break-in, the engine parts are going to be wearing in, ie. mating. That will create extra heat. You need non-synthetic oil so those parts can mate in properly. Synth. oil is too slippery and parts will take forever to mate. You need to run either more oil rich mixture or richer fuel mixture so that the oil can take away the extra heat in the engine during break-in process. After break-in (I think 5 gal. of gas) you can use synthetic oil. Some can be mixed at 50:1 or 100:1. Periodically check your spark plug because that's the best way to tell whether you're running the engine too rich in oil or not enough oil thus heating it up. If engine has too much oil the spark plug will be black and wet. The spark plug will be white if engine is running too hot and not receiving much oil. Oil removes heat and not having it makes engine run hotter. You could theoretically have a rich oil/gas mixture yet run the engine too lean causing lots of heat. Basically the result is that not enough oil is getting into the engine because either the needles are too lean or there is not enough oil in the gas. Just because you run synthetic oil doesn't mean your engine runs cool. Remember that oil absorbs heat and it takes it away thru exhaust. It's not about reducing friction between metal parts but about having a medium such as oil that absorbs heat and removes it from the engine. It's the same reason why heli pilots switched to 30% nitro. The gallon of that stuff has higher oil content that removed lots of extra heat from the heli engine thus helping it run cooler because all that nitro made for a hotter combustion. But that high nitro content help create more power in the engine. It was because of the extra oil in the fuel that made running 30% nitro possible, otherwise the engine would melt. Same with gas engines. You need oil that removes heat from the engine, plus you need oil for lubrication. Personally, I'm going to be removing oil from my gas and observe the spark plug to see if I'm running too hot. Right now at 32:1, the spark plug is way too black and wet. Next is 40:1 mixture, but after break-in and tweaking the needles.

Oww, I did that myself once....sold the cowl back to myself. Smashed my DLE55/Reactor combo straight in last October after not checking Rx batteries[&o]. Hadn't mounted the cowl yet; now I have a spare! Good news was that Jody from Valley View repaired my DLE, and though it was a little tighter than the original (7400rpm just before the wreck, 71-7200 on the new one at first), I now have over 30 flights on the new one at 14 minutes per, and she's loosened up nicely. Back to 7400 on a 22x8 Xoar...

That is true with the type of high performance planes Toni runs. I would say thatmost RC flyer,s (20%) or less use baffeled system for air flow.Most use the 3 times bigger outlet for air than the intake for air for cooling. Could be wrong....it would not be the first time! Capt,n

Love ya baby, and I agree with you

A word of warning about flying without the engine cowl, on some planes exposing the flat firewall area to the airflow will burble the air down the sides of the fuse and cause the elevators to become less effective.

It may not be a safe assumption that your plane will fly just fine without the engine cowl.