Hi gang,

http://www.rcuniverse.com/forum/m_3139357/tm.htm will explain why, this evening, I bought a new OS LA 40 for my Super Stick. (It's an entertaining little story, imo)

Anywho...never broken in an engine before. Obviously, my intent is to spend the evening reading and understanding OS's instructions, but just wanted to know if there are any tips or tricks that would be handy to know going in.

I'll be running Omega Castor/Synthetic 15% fuel (unless I learn this evening in the instructions that OS doesn't advise that for some reason)

TIA,

I broke in 2 OS LA 40's by the following:

In my test stand I run one tank of fuel through it according to the instruction manual.

I put the engine in the plane, start it, lean it just a little and do the break in in the air.

As the engine breaks in, (several flights) continue leaning it until you get max RPM then fatten it back up a couple of clicks.

Both of my LA 40's are 4 years old and still running great.

I did 2 tanks of rich, and then i began slightly leaning it. It worked well. These are very good engines and will be plenty for that stik despite what you hear. I love mine now that i have gotten to know how to use it and fly with it. I reccomend an 11 by 5 or 4 prop for the stick if your into just putt puttin around, but if you want speed then go to a 9x5 - 9x7

This is a great engine when it runs good.

Your fuel is the right type. I'd suggest a 10-4 prop for break in. This is an ABC/ABN engine. It should be broken in at a only SLIGHTLY rich 2 cycle mode. I'd also suggest a McCoy RC 9 or 59 plug. Run 2-3 tanks through it on the ground, then, if it will hold an idle and transition, fly it.

Dr.1

The OS manual recommends a 10x5 thru 11x6 prop. A 9 inch prop is just too small for an engine in this size range. A 10x4 would be OK for breakin but I wouldn't leave it on too long. IMHO

http://www.osengines.com/manuals/40-46-65la-manual.pdf

Chad,
A 9" prop is really too small for this motor. From the manual for this motor OS recommends 10x6-7,10.5x6,11x5-6. A 9" prop will cause the motor to over rev because of not enough load on it, and damage the motor. For the purpose of this discussion OS recommends an 11x5 prop for break in. The manual for this motor can be found at [link]http://osengines.com/manuals/40-46-65la-manual.pdf[/link].

Gboulton,
If you follow the break-in procedure that is in the manual you will do just fine, and the motor will last for a long time.

Hope this helps

Ken

I agree with almost everyone else. Follow the instructions and you'll be fine. For actual flying of the plane I would go with the 11X4. It's more of a 3D prop and will keep the speed down but give you gobs of pull. A 9 inch prop will over-rev the engine.

The key to propping an engine is getting the rpm's into the upper end of the torque range, not the upper end of the rpm range, although some higher revving engines have their torque and rpm limits really close to the same rpm.
The hard part is finding out where that torque range is. Not all manufactures will list that number.

As an example, My YS140 Sport says to use a 16X10 to get into the 8500 to 8700 rpm range which is maximum torgue, but red-line is 9500. I wanted more pull and good braking effect so I went with a 18X6 and ended right at 8700. Props can be thought of like this

Large diameter and smaller pitch means slower speed but more pull for takeoff and veritcal plus better braking for downlines and landing

Small diameter and large pitch means more speed but less pull plus your takeoff run will increase until the prop comes up to speed and slowing it down will be allot harder

The fuel you are asking about should be just fine.

Well, having thoroughly studied the manual last night, I've made a couple of decisions, and have one question:

1) I'm going to grab a couple of 11x5 props. I've BEEN flying a 10x6 on the Magnum, and may return to that (I'm a speed freak *grin*) but I'll use an 11x5 for breakin, and may try flying the stick with it a time or two.

2) I'm going to see if I can find a bit of 5% for break in...while I suspect, as you guys have said, the 15% would break it in just fine, the manual reccomends 5% for break in, 15% for normal running...might as well heed the manual's advice.

The big question I have is this:

The manual spends quite a while describing the process for setting the 'ideal needle valve setting'...normal stuff, start with it 1.5-2.5 (depending on which motor) turns rich, run it through the 4-cycle stage, etc etc...until one achieves the 'ideal' needle valve location.

Ok, fine...but it also says that this should be done once the motor is broken in.

However, in the section for breaking in the motor, it says, helpfully, 'start with the ideal needle valve setting and...'

Umm...unless I've missed something (very possible...I WAS educated in Kentucky after all), the manual just told me to set the needle valve AFTER break in, but to start break in by having the needle valve set.

??

You will be fine breaking it in with 15%, just run it a bit rich so it stays cool.

Looks like an oversight by the manual writers. Set the needle valve for break-in, and the do the break-in procedure. After that you may want to reset it for flying, but you should be good after breaking it. Like the manual says, lean it out a little bit for each flight after break-in. I have a good rule of thumb I use when flying, tune it to peak RPM and then turn it back 2-4 clicks to the rich. I like to see a bit of smoke in the exhaust when I'm flying. If you run it rich like that the motor will last for a long long time

Ken

Despite what the OS manual may say, an 11-5 is a huge load for an OS 40 LA (they also claim 1.0 BHP -- reality is ~0.78 BHP). It will turn at ~ 10,900 - 11,000 at sea level with that prop, but the torque peak is @ 12,700 rpm. An 11-4 will turn @~ 12,100 - 12-200 --- much closer to the torque peak. The 40 LA will spin a 9-7, or 10-5 right at 12,700 rpm -- perfect for max performance.

Well. you're not going to be much of a "speed freak" with an LA .40. No matter what the manual says, if you break in that engine rich, you'll ruin it. Also, I still maintain an 11 x 4 or 5 is too much diameter for that engine. Especially for speed.

Dr.1

I do the same thing.

Depends on what one finds to be 'speedy', Driver

I'm not sure I understand this...how will running it cooler with more lubrication during break in 'ruin' the engine?

Ken, thanks for the clarification on the manual. I'll follow the procedures in that order...establish needle valve position, then break her in.

Do not, and I repeat, do not run this engine in "four cycle" mode during break in. This is what DR1 is referring to when he says you'll ruin it. I don't care what the instructions say, you should never run an ABC engine sloppy rich. The problem is that the metals in the piston and cylinder wall need to expand during engine running, causing the correct "fit" between the two. When the motor is ran too rich, too much oil enters the firing chamber, and keeps the piston/cylinder too cool for this fit to take place. Therefore, the cylinder never really expands like it should, and the piston/cylinder fit is too tight. Running the engine like this for too long puts too much pressure on the con rod assembly, and can definitely ruin the engine. That being said, run it rich up to the point of four cycling, but do not enter the four cycling phase.

As far as props. On both of my OS 40 LA's, I run 10 X 6's. When I want to go really fast, I change to a 10 X 9, and the engine handles both props extremely well. I can't go any bigger, as these engines are both on the same plane, and any larger diameter will cause the nose of my fuse to be cut off

You will not get speed performance from these motors, no matter what prop you run, unless you run two of them together , or it's on a plane under five pounds.
JMO.

Ahh...ok, thanks 2slow...I think I see where our miscommunication was.

The manual says nothing at all about breaking in the engine in '4 cycle mode'. It refers to the fact that, initially, on first start, it will be running 'in 4 cycle mode' (which it describes as only firing every other upstroke of the piston...not exactly a '4 cycle', but hey, ok...I'll go with it). The manual explains this will occur because the engine is running VERY rich.

This is during the INITIAL process of setting the needle valve, and only occurs for a few moments, while you're closing the needle valve from its initial 1.5 turns open position...in other words, it only runs this way for a few seconds, on the first start.

When DR1 said not to break it in rich, I was confused, since the manual and nearly everything I've ever read on RCU specifically says that is EXACTLY what you do...run it richer than the max rpm setting of the needle valve. So i was wondering if he was proposing that the engine should be broken in by running it leaned out to max rpm the whole time *heh*. Didn't make a lot of sense at the time, but hey...i'm the newbie, maybe he had some tip I hadn't read before.

And yes, 2slow, I can see exactly what you're saying...the point of the breakin is, specifically, to allow components to expand and seat correctly...running it far to cool would, of course, prevent that from occuring correctly.

As it turns out, the OS muffler will bolt straight up to my Magnum XL 40, so I may just do that so i can fly the stick again today or tomorrow, and break the new motor in this weekend when I have more than an hour or so to kill.

Thanks again for the input, guys.

rich but not TOO rich.

Hi!
A 11x5 or a 11x6 (APC )is what you should use, at least if you fly at sea level and going to use it in a high winged trainer like the Kyosho Calmato or a plane like it.
A 11x4 or a 10x6 is not so good for this kind of airplane. but for a 3D type of airplane a 11x4 might be wort thinking of.
Remember this engine is a "puller" ...it doesn't like to rew much so keep the rpm down to between 10000-12500 rpm.
5% nitro is all it needs to be tottaly reliable, 10-15% nitro is owerkill!!

Regards!
Jan K
Sweden

gboulton,
Run it rich but DO NOT 4-cycle it! I've seen guys kill ABC engines like this... Now a Ringed engine is one to 4-cycle..
Breaking in a .40 LA is not all that difficult.. Listen to the guys here and it'll be fine..

And Dude.... You gotta quit with the KY stuff

When you flying with your uncle again?

Well, as it turns out, it wouldn't even start that rich...got it started with the valve turned about 1 turn, rather than he 1.5 the manual suggested. Anywho, have already found the optimal needle valve setting, and rolled it back 30 degrees, per the manual, so I'll start the breakin process tomorrow.

As for flying with the uncle, I'm going down there a week from this Saturday, and will PROBABLY take the Murray route to get down to Puyear where we fly. I'll PM you more details when I'm through with this post.

Thanks for the input, guys!

Jaka, you & I really disagree on this one. The torque peak of the 40 LA is @ 12,700 & you need to at least reach that to extract usefull power from that feeble engine. With the power peak @ 13,400 it isn't exactly a rever, but it can't push water downhill with an 11-6, regardless of the airframe it is fitted to.

An 11-4 is a good trainer prop for it, but even with that it can't reach the torque peak on a cold day at sea level.

I have an OS46 FXi that came with the NexStar. It came with an 11x5 prop but my instructor said to switch to APS 12.25x3.75. I am having a terrible time getting it to throttle up from low to high without the engine cutting out. We have followed bubbagates recommentdations on setting high speed and low speed. I keep moving low speed very minimally too. We are running it slightly rich to rich. I have run 1 1/2 gals. through it so far. We are only getting 9 mins. on 12 oz. tank and my instructor dead sticks a lot when it cuts out. We find that the prop stops nearly verticle and you have to break it free with slight pressure. Sounds like it is binding. Instr. says it may be extremely tight engine but when it breaks in it will be the best engine I'll ever have. Everyone else says it should only take 2 or 3 TANKS to fully break in an OS. Another member has a NexStar same as mine, and his engine runs great. He has never had any problems. He has same instructor and same fuel.

THERE IS A QUESTION IN HERE. SHOULD I GO BACK TO THE 11X5 PROP? I TALKED TO OS AND THEY SAID TO SHIP IT BACK TO THEM (WITH NO GUARANTEE) - BUT THEN I WON'T HAVE ANYTHING TO FLY.

my advice is ignore the manual i have the 46 la and neither of the settings they state were right!!!.start with needle 3 turns out then prime it by putting finger over carb turn prop 6 turns not 2 as stated then connect glow plug and use starter to start it.when shes running just close needle valve till she starts running in 2 cycle mode then run a tank through it idling,then id put one more through it and close neddle a bit to lean her out more.give her some revs and just keep reving her and backing off the throttle to idle till the tank is empty.then go fly it and after each flight close needle a cpl of clicks each time till shes running at her peak!!.my 46 la is a great running engine so im sure youres will be just as good!!.

mcdanman2003,
I've got 6 46FX engines. Although they say only a couple of tanks of fuel to break in it has been my experience that it really takes about 20 or 25 flights before the motors really start to loosen up and run well. Just give it a bit of time and it will get there. These are great engines.

Ken

*heh*

It would appear I started a more spirited discussion than was my intent.

Ah well...I've done the initial start, found the 'ideal' needle valve setting, and just now did the first tank of fuel at full throttle with the needle backed off 1/2 turn from ideal, per manual's instructions. (forgive me if, when there seems to be considerable disagreement, I decide to do what the manufacturer says to do )

Thus far it seems like a good running engine (there were no hiccups of any kind during the full tank) and, judging from picking the aircraft up while running, it's not much different from the old magnum 40 in terms of thrust, so i should be relatively comfy flying the stick with the new motor.

Ken, I'll keep in mind what you've said about taking 20 or so flights to really get good and loose. I'll probably spend the weekend flying her 10-15 times, slowly adjusting the needle back toward max rpm, hopefully winding up by the end of the weekend at a couple clicks shy of max RPM, as we discussed before.

Really want to thank you all for your responses and thoughts in here...while, admittedly, i may have disregarded some advice in favor of the manual's suggestions, it's been an educational thread in terms of clarifying some of the processes and purposes involved in breakin.

[>:] I tell you, all this advice (good and maybe bad) and what does he do? He goes and follows the mfg instructions. We coulda stayed at home. Go figure.

Enjoy your new motor!

My RTF trainer came with a 10-6 prop on a .40 OS LA so I figure that is probably a good range to be at. Course I'm not experienced enough to really know but thats my .02 cents...