For you guys with more experience with engines.. please first define what exactly breaking the engine means and does and then please explain the best methods for doing this. mine is a O.S
50 ringed. Thanks

Some people go to great lengths to break in an engine. I don't.

Usually, with a new engine, I will jusy fly the first 1 or 2 flights with the mixture very rich, then for the next few flights, slowly lean it out to where it should be.

If you post this question in the engines forum, you'll get a much more defined answer.

I do the same as MinnFlyer. I run it rich for the first few tanks then slowly lean it out just a tad on each subsequent tank until its where it needs to be. Has worked well for me thus far. If I get a real finicky engine I'll run a tank thru while on the ground (but I've never run more than one tank thru while on the ground). Hope this helps!

Sound like combat fliers it is not going to last long enough to get broke in. Follow instructions that is why there , there.

If you bought the engine new, the break-in instructions were in the box. The ring needs to be seated properly to expect any kind of useful life out of the engine.

Breaking in (or running in) means to mate all the running surfaces together better than what can be achieved by the original machining. This is especially true of ringed engines because the ring(s) can never be machined to be perfectly round and they also need to bed into the groove in the piston. The liner will have hone marks on it which make small pockets to hold extra oil as the ring beds in and these will slowly get worn down over time. Also the bushes at both ends of the conrod need some running to bed in properly.

When running in any engine you should always have some castor in the fuel. Castor likes to "stick" to metal but synthetics tend to just slide off.

Usually it's good advice to follow the instructions but for years OS included the ringed running in instructions with all their ABC engines and have only just changed them. Chances are they now have ABC instructions for the ringed engines

Use the smallest prop that's recommended or go even smaller if you like. This is to keep the load down, mainly on the conrod. A ringed engine has to be run in very rich so open the needle maybe 4 or 5 turns. For the first one or two tanks it should be so rich at full throttle that you may even need to keep the glow starter on. If you tach it you'll probably find it's down around 6 or 7K revs. Give it a couple of tanks like that then start slowly leaning it out just a little each following tank for the next 20 minutes or so. Make sure it never breaks into the normal 2 stroke sound though. If you don't know the difference between the rich running 4 stroke sound and a 2 stroke sound then you soon will After maybe 40 minutes or so you can lean the needle so it's just barely into a clean 2 stroke for a few seconds then back into a 4 stroke. Do this for a tank or so and then you'll be ready to fly it. But for the first few flights keep it rich because it still needs more running in. They can take several hours to be completely run in so don't rush it if you want an engine that'll last just about forever.

Downunder,

That was a very great post! following the instructions does not give you the reasons why and if you dont khow exactly what you are doing you can not modify it for different situations. Thank you for the great info.