Sounds like a good proceedure. But also too complex. I just run them at a full four cycle for a tank then run it leaner. At full throttle.

If four cycling glazed cylinder walls, how come the control line guys don't seem to have this problem?

I recall growing cast iron pistons to get additional life out of the old lapped iron engines. But that was in a kitchen oven turned to broil for a considerable amount of time. I doubt the rings in our engines are getting hot enough to do this. Maybe the first thousandths of an inch or so. Also cast iron growth is cause by the carbon nodules and perhaps other crystals in the metal expanding. Steel and aluminum do not have carbon nodules, though the high silicone aluminum does have silicone nodules. Still I don't think our engines benifit from heat cycling, though it does help to break in an engine quickly (high pressure, high heat) without overheating it. Though I prefer to just let them run. After I am confident they are running well I usually find something to do at the nearby work bench, or water the garden or something.

Let's read up on these "Hard facts about engine break-in", shall we ?
From Lycoming engines:

Hard Facts About Engine Break-In The basic rule which applies to most
normally aspirated Lycoming piston ... A good break-in requires that
the piston rings expand sufficiently to seat with ...
www.lycoming.textron.com/support/publications/ keyReprints/operation/engineBreakIn.html - 12k - Cached - Similar pages


Most people seem to operate on the philosophy that they can best get
their money’s worth from any mechanical device by treating it with great
care. This is probably true, but in many cases it is necessary to interpret
what great care really means. This is particularly applicable when considering
the break-in of a modern, reciprocating aircraft engine. Aircraft owners
frequently ask about the proper procedures for run-in of a new or rebuilt
engine so they can carefully complete the required steps. Many of these
recommended break-in procedures also apply to engines which have been
overhauled or had a cylinder replaced.

For those who still think that running the engine hard during break-in falls
into the category of cruel and unusual punishment, there is one more
argument for high power settings during engine break-in. The use of low
power settings does not expand the piston rings enough, and a film of oil
is left on the cylinder walls. The high temperatures in the combustion
chamber will oxidize this oil film so that it creates a condition commonly
known as glazing of the cylinder walls. When this happens, the ring break-in
process stops, and excessive oil consumption frequently occurs. The bad
news is that extensive glazing can only be corrected by removing the
cylinders and rehoning the walls. This is expensive, and it is an expense
that can be avoided by proper break in procedures.

http://www.lycoming.textron.com/main...neBreakIn.html

Any more questions ?

FBD.

Give it as rest Dave
We get it no one knows more about engines then you do ok.
you win
you are King
as the Big Bopper says your incredible,
We bow to you

OK on Lycoming- but on these rinky dink little engines - honing will just rip the shiny treatment from the walls. it is extremely thin and never honed.
anyway run em fast don't over lean getting em hot -go fly - slow running break in on these is a waste of time

I don't know where this load of misinformation came from.

Aircraft engines are set to run with a perfect fuel/air mixture at sea level
They are not set to run rich on the ground. Running rich will cut
down on the power available, which is full power. As the aircraft
climbs the mixture become richer than at sea level, the same as your
car does....losing power at high altitude.

This is when the mixture control of the carb is leaned out. This allows the
engine to once again make full power, adds to the fuel consumption
(mileage) and prevents harm coming to the engine from a too
rich mixture. Spark plug fouling, oil contamination and other problems
that need to be avoided.

Aircraft engines do not have looser clearances on the ground than
they do in there air. This is about as foolish a notion as I have ever heard.

There better not be any blow-by in the aircraft engine at any time.
Most aircraft engines use an extra set of rings to insure that ring seal and
compression are kept as perfect as humanly possible, and that blow-by
is eliminated at all times.

Sport pilot, please quit quoting me, and bringing up these stupid notions just
to try and prove me wrong about something.

I am quite sick of your badgering. Get some facts instead of these mindless
claims. And BTW, I am a Private Pilot. Don't try to B.S. me with this stuff.

FBD.

All true, Dave. Ringed engines need to be up to temperature to seat the ring.
Running an engine sloppy rich will insure the engine will be a dog
for its lifetime. That's a fact. Keep up the good work, the detracters will
fall by the wayside in time.

M.B.

So you second the suggestion to ignore what the engine manufacture say to do while breaking in their engines
why would they bother to print specific guide lines about running them rich for break-in then just to humor us.
But ya know what? model engine makers have said run um rich long before AlGore invented the internet
making it so easy to spread misinformation
I'm going with the engine makers surely there smarter then anyone on this forum when it comes to whats best for their own engines

Dave,

The Lycoming article doesn't address the issue. The issue isn't high power settings, but running rich. The four cycle break in is done at WOT.

So explain the control line four cycling their engines for every run. Why do their engines not glaze?

No one has explained that yet.

enough of the armature hour I am going over to the manufactures forum and ask the question there lets see what kind of answer we get from them
think I'll start with YS since I have one and they say run rich for break-in
anyone want to say YS makes junk and doesn't know anything about model engines
ok good

I didn't say to ignore the Manufactures recommendation. Show me where I said that.
Do not try to put words in my mouth or mince them. Take what I say at face value.
I offered my own technique for break-in, nothing more.

Take it or leave it.

FBD.

Well everything your saying goes against what the manual says to do
then just what are you saying

OK everyone Dave didn't say ignore the manual
I drew that conclusion from all the posts about not running an engine rich for breakin
I apoligize to Dave

The answer to that one is quite simple. C/L engines are broken-in just
like any other engine....at full throttle. They adjust their engines to a four cycle
speed for flight to keep the speed down.

They have no throttle. The four cycling is the "flying mode"....

....not the "break-in mode".

Once the engine is properly broken, they can agjust them for flight any way
they see fit.

FBD.

I was refering to piston rings, not armatures.

Let's look at the YS manual, shall we ?

3. "the needle valve should be set so that the engine in running at a rich setting".

Gosh willikers....that's what I said too, Remember I said to set the engine at 500 RPM down from full peak. That is a rich seting.

YS: "run the engine for 20 minutes at this setting"

WOW !!....what a coincidence....that's what I said. Run the engine for 20
minutes to complete the ground break-in.

Keep in mind, the original Members post was in reference to a GMS 1.20 engine.
You are now changing horses in the middle of a stream to 4-cycle engines.

I get my references from a lifetime of experience, not from the Internet.
I do read the operators manuals, and I still have the manual for every new
engine I have purchased.

FBD.

Go back and look at post #26, where I gave my short version of the break-in.

Look here at #2 what YS says to do when the engine is first started.

Looks alot like what I said, huh ?

skiman....please find someone else to argue with, OK ?

Thanks.

FBD.

what ever

Are you going to switch to Magnum now? Show me where it says to
run the Magnums engines sloppy rich in the manual.

Motor Brain

no I started with magnum but you joined in late
back in post 30 if you want to read it

step 4 of the Magnum xl52 single cylinder four stroke engine manual says
this is under break-n Procedure
details
4. Once the engine has started, at a full throttle setting ,adjust the high speed needle setting to a very (or ''sloppy'') rich position.
let the engine run for two or three minutes. Stop the engine

their words not mine

Dave I have a brand new ys 140 in the box I read the book too

That is the reason some of these posters said phoey with the manuals
and they stick to the time proven methods. Like Dave said, you wouldn't
run a chain saw or a generator like that, Why would you want to run
a motor like that.

But then just to state the obvious, you came here to argue.

Bye bye.

Motor Brain

[img][/img]

GOOD BYE

These are not chain saw's and generators. They use differant fuels, oils, operating temperatures, and less sophisticated carburation. Most engine manuals for two stroke ringed engines say to break in four stroke mode. And most model engine guru's, apparently just not the internet engine guru's.