Ok Im starting my engine for the very first time and I know Im supposed to run it rich and run thru a few tanks to break it in. I have a question about the tuning needle tho. Im under the impression that clockwise is lean and counter-clockwise makes it rich? Also how many turns does it take to go from lean to rich? I dont see a difference in asnything and there;'s no visible indication to let you know when you're actually running rich or lean. I also I cant find the info anywhere. Thanks in advance.

I am new at this as well but I have been flying for a few weeks and yes depending on the engine clockwise will lean the engine and counterclockwise will richen the engine. What engine is it? Are you bench running it or running it in your plane? You should run the first tank on a bench or in the plane with the plane against a stop or with someone assisting you by holding the plane still. If it is an Evolution engine than it has been broken in at the factory. Start the engine and leave the glow driver on and let it warm up for about 30 seconds and then run it to full throttle and back to idle. You can then remove the glow driver and run the engine back to full throttle and make small adjustments until it starts to stall a bit and then turn it back a couple of clicks. If it will allow even 3 clicks to richen it up. Then you should back it back to idle and let it cool a second. Then run it up to full throttle, and so on and so on. If you go to your engines web site they will have the exact break in recomandations for it and what oil content and what % of nitro etc. You should look it up or it should be in your owners manual. I have been told it takes 3 or 4 tanks to break them in. Don't know if this helps but it's the best I can do. Good luck and hope you enjoy!!!! Mike

You did not say what motor it is but here are my suggestions.No there will not be any visible difference from rich to lean other than the a mount of smoke it will make when running.This is What I recommend you do. Open needle 4 turns counterclockwise ( very rich). While running carefully turn needle in clockwise, possible 1 turn. It should still be rich, not running smoothly. Do this with throttle fully open. You do not want to lean it out at this time. Continue doing this for several tank fulls but after first 2 tanks you can lean out from time to time but back to rich each time. Just do not overdo with leaning it. Depending on the engine it could be ready for flight sfter 3-4 times on bench but some may take far more to break in. Use 10% nitro fuel for this with 18 to 20% oil.
Be very careful the prop can do major damage to fingers.

Thanks for the replies. Yes I didnt mention the engine, its a OS .46AX ABL. So 4 full turns counter clockwise will make it rich? I didnt know if I was in fact running it rich, at least this is some kind of measurement to go by. So I guess I;ll do that. Any other words of advice now that you kmow the engine?

I dont want to sound ignorant or anything but when you say 4 full turns are you refering to clicks or full rotations?

By the way that is a very good engine, that is what I wanted to buy and thought I had bought one on ebay and the guy pulled it from the auction after it was over kinda stunk if you ask me so I bought the Evo at my LHS. Everything I have read said that the Evo was the second best engine right behind the OS .46 AX Good choice and enjoy. MIke

http://www.gettingairborne.com/engines.html This is a site one of the guys gave to me it should help with all your questions. Good luck. Mike

4 full turns would mean 4 full turns... not 4 clicks. A click is not a full turn.

Not trying to insult you sir but 4 full turns will mess it up bad. That is the only reason I asked. No offense meant and I hope none taken. I sent you a link one of the guys sent me and it really helped, If I ticked you off sorry just dont want to see you throw it way out of whack thats all, OK Good luck and later. Mike

Thanks again for the replies, especially you Mike. This is getting confusing lol... Basically I want to run the engine rich. So... How many FULL TURNS counterclockwise do I need to turn the needle to make the rich?

You don't want to make any full turns just a few clicks will richen it up. If you got the link I sent it will walk you all the way thru the process and I feel your pain. I had the same questions when I started and the guys on here helped out a lot. You should be able to turn it 3 or 4 clicks and when it starts sputering and blowing a lot of smoke it is running rich. Hope this helps and again you bought the cadillac of rc engines in the 2 stroke class. Good luck and have fun. Mike

Opening the needle valve 4-5 turns from closed will ensure you have a good rich starting point. Here are some good instructions for breaking in all ABC/AAC engines. It's worth the time to follow these directions, as an engine is an investment and you want it to last for as long as possible.

http://www.jettengineering.com/ (look under the instructions/tech section for engine break-in).

Once you have it broken in, tune it for performance using your flight propeller (not the breakin prop). Use a tach and slowly lean the needle valve until you get max rpm and it barely starts to fall off. IMMEDIATELY richen it up (1/2 turn) and let the motor cool off. Once cool, start it up, slowly lean to max rpm and then immediately back it down about 800-1000 rpm. This will allow the engine to unload in the air without going lean. Once you have it set 800-1000 rpm down, do the "pinch test". Quickly pinch the fuel line at the carb - you should hear a noticeable increase in rpm. If you don't richen it up a bit more.

Good luck!

Do not use throttle to alter engine speed during several motor runs do so only by altering needle valve setting from rich to lean and back to rich. Allow it to run at lean settings for no more then 1-2 minutes each time. If you get it too lean you will notice an abrupt reduction in speed because it's overheating NG.After running on bench in this way you can continue the break in in the air but set it to barely lean then back off needle 1/4 turn. At this time you now may use throttle to control speed. Good flying, hope you have an instructer or don't try it. Get yourself someone to check plane out for trim etc.

The best instructions you can get are found in three words: get experienced help.

There is no set number of turns. Four turns seems far too rich to me, but I don't have a 46AX. I've got a 46FX, which would need somewhere around 2.5 turns to run very rich. It depends on the fuel, the air temp, humidity, etc.

You'll get a lot of varying advice from people of varying experience levels and skill. What you choose to do is up to you, but the three words I mentioned will get you up and running in the safest, fastest, and best way. You're getting an instructor, right? Why not wait until you meet them at the field the first day to run the engine? An AX doesn't need any significant break in time. Run a tank through it on the ground while you get briefed on how to properly fuel, prime, start, and adjust your engine. Let it cool, then take the trainer up for your first lesson.

I know it's hard to wait and everyone wants to run their engine, but you'll have the greatest success in doing what I've suggested. The fun in this hobby happens in a lot of different ways. Burning up your new engine or damaging it by running it too rich (yes, that does happen with ABC-type engines!) probably isn't fun.

As Fxrs_tim pointed out, it will not "mess it up bad", but rather establish a safe starting point to break in the engine.

Once it's been started it can be leaned over time to a more optimum setting.

That is wrong and assumes everything is already set perfect and life is not perfect. You must have one of those Evo's with limiters on it that disallow conventional tuning. Closing the needle completely then reopening 2.5 to four full' turns is SOP practice and assures a safe starting point to start the leaning process when starting an engine for the first time.


To the original poster as had already been said you need to wait and get experianced help before you start that engine.

Fwiw, I have a pair of .46AX's in a twin, and I've set a few for newbies. When new (or after removing the needle), most OSes seem to do well with 2.5 turns out. That almost always gets you rich, but not so rich that the engine won't stay running. Just a datapoint. My .46AXes, on a side mount, with APC 11x7 props, OS #8 plugs and Omega 15% fuel, at about 300ft above sea level, I set them at 2 turns to start with if I have to remove the needle or something (like taking off the cowls for maintenance).

The exact needle position will depend on fuel, air pressure, humidity, prop, and so on.

Personally, I'm not a fan of running an ABC/ABN/ABL engine really rich for any amount of time. Running the piston/liner fit really cold just wears them overly fast, and you don't get as much power as you otherwise might (though for a first engine, loosing some top end RPM is probably not a big deal). You don't want to run lean either, since that results in too much heat in the conrod ends, and can destroy the engine if the conrod seizes and breaks.

So, I like to mount a slightly smaller prop (I used a 10x6 on my .46AX). A smaller prop means less load on the engine and less strain on the conrod.

Then run the engine so that it's just breaking in to a clean two-stroke whine. No idleing, it's start engine, go to full throttle, set needle (slow lean until clean two-stroke noise is heard), count to 10, kill engine.

After the needle is set, I don't touch it for a few runs, just let the engine cool down, then run it again for about 20 seconds. Then 30 seconds. After that, I'll do some of the RPM cycling in a longer run, using the needle only. Lean it out to almost peak, then back it off, then lean it out, then back it off, but never into that "blubbering" 4-stroking rich setting.

Now, for engines with rings, it's totally differnet. You need to run them really rich for a while, keeping everything nice and cool and well lubricated.

Oh, and fwiw, Evolution engines aren't broken in at the factory, just test run. You can tell they aren't broken in because the idle mixture will often change quite a bit over the first few tanks of fuel, and all the parts work together. You often have to lean out the idle a bit, sometimes you have to remove the limiter to get the low end lean enough (I took the limiter off my Evo .46, and off of several students' engines to get them to transition with out sputtering).

Don't know where you are getting your info but 4 full turns will not do anything other than cause it to run very rich. Which is a good point to start from. Thereafter you can gradually lean it out but continue to run rich for several tank fulls. As I stated after 2-3 tanks lean out to normal 2 cycle by using needle valve allow to run leaned but back and forth between rich and lean for couple tanks. DO NOT use throttle at this time to alter speed; this will be done after several tanks that have enabled motor to break in piston with liner. After this usually break in can continue in the air. Do so with rich runs, bring to lean then back out couple clicks. Of course break in method can vary some depending on particular motor, ringed, abc,etc. but this method will do no harm and will work for any motor. Some will take longer to become FULLY broken in that's all.

That's just not the right way to break in an ABC-type engine. It needs to be slightly rich, not blubbery, 4-cycle rich. Having it that rich will not accomplish anything positive, and may actually damage the engine. ABC-type engines need to come up to their designed operating temperature to have a proper piston/cylinder fit. Keeping it too cool just puts undesirable strain on the engine.

I'm couple days late in replying to you but reply I must. You are right about ABC (non ringed engines) requiring to be run at proper temp to properly break them in. However, the best way to do so is as I had stated. Run rich to lean to rich to lean do not use throttle at this time run wide open. Alternating the mixture setting allows engine to reach desireablle temperature but then to cool some. If I'm wrong on this guess just been lucky to still have all my engines(about 30) still running great from 50 yrs ago to present. By the way I have run diesels, gas, ( even those that were spark ignition with coils condesers etc.). I had suggested it be started ( blueberry cycle rich)) only for a starting point for a new person. I come here to beginners forum to be helpful if possible and I even learn something from time to time but do not like being told by someone that thinks he knows it all. That I'm wrong. If you had read and digested my entire post you could not find fault

I don't know...most engines comes out of the box at a rich setting ready to be break in.
99.9999999% they fire up on the first try if I use an electric starter.
Depending where you live, outside temp...etc. You might need to trun it 1/4 trun eiter way.
I've yet had to un screw 4 complete turns on any HSN in all my years of R/C or anything else.
And I've yet to turn any settings more than 1/4- 1/2 at a time, especailly during a break in.

Generally 2 1/2 turns out is a rule of thumb for a starting piont for any kind of needle setting.

I worked at a power plant for years and came acrossed all kinds of comtraptions.
I have all kinds of certificates from catiplliar.
I even took a college course on small engines....so what

You have aroused my curiosity by your reply. What's the big deal about how many turns you start with? Yes usually 2-3 turns are sufficient. The main thing is to have it very rich then lean it out some. This guy I sent the reply to didn't know what was rich what way to turn needle etc. If you have read the original post as well as the one after that it was apparent that the purpose was to start rich then go less rich then lean then back to rich throughtout several tanks. What has it to do with your caterpillar certification? I was an aircraft mechanic in Navy during WW2, does that mean anything? NO!!I have been building flying RC since single channel escapements through all phases of equipment changes. and now includeing electrics. Does that mean anything? I would think so??? However, as I have said there are still things I can learn and often do. I'm on this forum to try to help those just beginning. If someone decides to be pickyune about 2-3-4 turns on needle they fail to see the intent. Yes ABC motors require different technique to some degree and think I mentioned that there will be differences with different motors. Basically though perhaps the most important thing is read manual if you have one. If not choose what you individually consider your best response to post and play it safe.

Different technique to some degree? What you described in your other post is more along the lines of what a person would do with a ringed engine. It's not appropriate for an ABC-type. Thankfully, most of these engines are fairly durable. ABC-type engines are very, very easy to break in if a person keeps their general operating principles in mind. Think through how they work, and one method for breaking them in makes much more sense than others. This plays out in practice, too.

In truth it doesn't have to be very precise. Get it up to temp and let it run. Run one through, then fly it a bit rich. That's really all a person has to do. Anything more is personal preference.

As I said above, if you use the ringed engine style break in on an ABC engine, you won't break the engine. You WILL reduce the power the engine will eventually produce though. For sport flying, most guys really will never know or care if their engine is running 2,000rpm down from where it could have run with a better break in.

So, if you want to run your ABC engine really rich to "break it in", go for it. You won't blow up the motor.

However, if you want to get what the engine can deliver when it comes to power, then you need to do something different.

This IS the beginners forum, and for a trainer, there's nothing wrong with wearing the piston a bit much. But it's funny, I see a lot of guys who come to a competition with an engine they broken in "the way they always did it" and wonder why it is that their new engine is so much weaker than even my old beaters. It's the break-in.

A beginner with their first engine isn't really harmed with a rich break-in. But more information never really hurts, so knowing that there is a another way that will produce more power from future engines isn't a bad thing.