Ok, I am new. I want to break a new engine in correctly. ANy good source for the procedure.

THanks,

First thing we need to know is - What engine?

The instruction book that came with the engine?

The instruction manual that comes with the engine is probably the best source for the break-in procedure that you'll find. Since you didn't mention what kind of engine you have there really isn't any way to give a specific break-in procedure to you since different types of engines have different break-in procedures.

Ken

Well, that is why I came to this site.

Thunder TIger Pro 46 - new
OS FX 46 - used

Should I break in a used one that I replace bearings on. Seems like a yes.

I am not sure I have manual on either.

Normal break in procceedure is more about seating the piston in an ABC engine. With the used engine I would just run it rich for a tank or two (I always run my engines slightly rich even after break in)
I follow the OS procceedure on my TT engines. Start engine, tune to high rpm for 5 seconds turn 1/2 turn rich for 20 seconds, reapeat and slightly increase high rpm time as you go for two tanks, then run rich for the first gallon of flying.
Some people just run a new engine rich and fly right away with no problems.

Check towerhobbies.com. They usually post the manuals in pdf format. Also check the manafacturers website. They also post them on there.

The manual for the TT .46 Pro can be found here:

http://www.acehobby.com/ace/PDF/Engine/PRO_Eng.pdf

The manual for the O.S. Max .46 FX can be found here:

http://manuals.hobbico.com/osm/50sx-...1fx-manual.pdf

I got the Thunder TIger very cheap and it is still in the box. What does the ABC mean on the box. I notice it was mentioned in the string above.

THanks for the tip on the manuals. I will get them.

It's generally NOT recommended to run in an ABC engine with a rich setting. The cylinder is tapered to form a very tight fit at TDC. When the engine temperature comes up to normal, the brass cylinder expands more at the top to give you the fit you want. If it goes lean then the cylinder expands even more which prevents a seize-up.

Put a prop on about a size smaller than normal flight and start the engine. Bring it up to full speed immediately then back off perhaps a click or two of the needle. Many short runs with a cooling off period of 5-10 minutes is preferable to fewer but longer runs.

ABC is the materials the Piston, cylinder and piston sleeve are made of or something to that effect A=aluminum C=copper (I think) B=brass. But it also tells you that the engine has no piston rings, it is a tapered fit.

Really? I run all my engines rich as do the much more experienced fliers at my club who have some very old ABC engines that still run like new.

This forum is great. I feel like I have instant answers to all my questions.

Thanks to all.

There is an extensive article on breaking in tapered bore ABC engines here on RCUniverse by Dar. Do a search and you should find it. Or, post to the engine forum and someone will point you in the right direction.

Dar's advice is to break in the engine moderately rich, but not sloberingly rich.

Here is the link:

http://www.rcuniverse.com/forum/m_18..._1/key_/tm.htm

...more information than anyone could ask for.

I thought it was A=Aluminum B=Brass C=Chrome, am I wrong? (Asking not telling)

You are right, I am not thinking right today.And some engines claiming to be ABC are really ABN N=Nickle (sp?)

Somewhat contrary to Dar's thoughts here's an actual experiment I did to see what would happen if a new ABC was run extremely rich.
http://www.rcuniverse.com/forum/m_28..._1/key_/tm.htm

What I learned from that was the best setting to start running them in was at a point right on or barely above the break from a 4 stroke to a 2 stroke. This is usually somewhere around 2000 below peak revs. I start the first tank at this break point and the revs increase slightly as the tank empties. At the beginning of the next tank I reset the needle so the starting revs match what it was at the end of the previous tank. And so on for several more tanks (about 5 minute runs each). This gradually increases the temp of the engine and allows the parts to adapt slowly to the increasing temperatures.

After they're run in I also run them quite rich for flying. Most of mine are used in CL stunt so they spend their life in a continuous 4 stroke but my RC engines are also kept quite rich.

Yes. Nickle is not quite as hard as chrome and does not require as much breakin. It is also not as toxic to the environment. If applied correctly in the manufacturing process (and enough of it), durability should not be an issue.

Keep in mind that it also depends on what you're trying to get out of your engine.

If you want peak power out of an ABC/ABN engine, then you want to get the piston/liner up to temp quickly and keep it there. Running the engine "4-stroking" or overly rich will wear the piston/liner fit a bit and reduce peak power. HOWEVER, if you intend to fly the engine at that kind of needle setting, then that's what you want! The piston/liner fit will work itself to be exactly right for whatever RPM and temp you run the engine at over time.

Break-in in the small 2-strokes is actually more about the connecting rod and it's bushings than anything else, btw. If you run lean during breakin, that's where things break. You need enough oil and cool temps on the conrod to keep the bushings from seizing and causing a broken rod, but you want heat on the piston/liner. So you use a small prop to avoid stressing things.

In an ideal world, for max power, you kind of know what kind of RPM you want out of the engine. Last one I broke in was a Magnum XLS .15 I'm using in combat, where I wanted max power. So I used a small prop and a tach, and ran that engine right up to the RPM I want later (20k) for just a few seconds. The needle wasn't fully leaned out, but it wasn't really rich either. I ran for about 10 seconds, then let it cool totally. Then did it again for several cycles with increasing run length. After a tank of fuel, I put on the prop I'm going to use in flight, and brough the engine up close to what I want RPM wise for a little bit. I then flew the plane a few times, taking it easy on the engine.

Here's a link to how Dubb Jett suggests you break in.
http://www.jettengineering.com/

But, as I said, that kind of break-in is what you want for peak RPM out of an engine. Most sport flyers aren't going to care if they "could have" had another 500-1500rpm out of the engine with different break in. And frankly, except for my combat competition engines, I don't either. The flip side is that if you run an ABC engine really rich for a while, then change props/fuel and try to really peak it out at high RPM, you'll get a lower RPM than someone who broke in for high RPM.

So, unless you're racing or something like that, just run the engine a bit rich. A tank on the ground, then to fly. With an ABC engine, that's all you really need.

Oh, you will notice that the idle will be a bit rough at first, and engines that use real chrome do break in slower (a good thing), and it sometimes takes a while before they idle well. Also expect the idle mixture and even the high-speed mixtures to change a bit as the engine breaks in. I have a TT .46 around here somewhere that really went through some wild low speed changes as it broke in. Of course, I got that engine used off of someone after they crashed it on the second flight. They thought they had a bad engine, what they really had was a rather nice, tight, un-broken-in engine.

And one last thing, most engines come with a piston that's been heat treated a bit, or maybe it's something with the alloy, I don't know. But there are a few, like my Webra .25s, where something odd happens after the first run. Before the first run, they don't seem to have a very tight "pinch" at the top of the stroke like they should. But after the first run, they get really REALLY tight. As I understand it, the high heat encounted by the piston can change the structure of a the metal a bit, and that can cause a very slight change in size and thus compression or "pinch". I mention this because normally you want a new engine to be really tight. When I got my first Webra, I was sure I had a lemmon, it was so loose. Then I ran that thing, and it became seriously tight and really put out the RPM. OS engines that I've used don't seem to do that, they always seem to be at their tightest when new.

Thunder Tiger used to be ABC (aluminum piston / brass cylinder / chrome bore). Now they are ABN (same but nickle plated bore). If your engine came in a black box it is ABC. Red box versions are ABN.