I just purchased a Nexstar and read through all of the manuals. The Hobbico manual says nothing about breaking in the engine but the OS manual does and goes into detail how to do it. I'm very familiar with nitro engines used in ground vehicles and the importance of breaking them in properly.

What does everyone suggest to break in the OS 46? Should I follow the OS manual and run a tank through it on the ground at full throttle richening and leaning it out every ten seconds? I've never dealt with plane engines although I don't think they are much different than their ground based counterparts.

Thanks...

swimman,
I fly OS engines almost exclusively. Every engine I have I break in using the procedure in the manual. Use the procedure in the manual and you can't go wrong.

Ken

I agree with Ken on this one.

Do exactly as the manual says and you'll end up with a great engine that's strong as an ox and reliable as all get out

In the NexStar manual I received it said the engine was broken in at the factory. Double check your manual. If you do not see this (it may have changed since I bought my NexStar last year) then definitely follow the engine manufacturers break-in procedure. I may be wrong bit it wouldn't hurt to break-in the engine again.

I think I do remember the manual saying something about the engine being broken in but I'm not sure it was. I have not taken it apart but from my inspection, it looks as if it was never run.

Although the engine is allegedly broken in, in my experience helping two others with their NexStars, the engine will work better if you run a tank through it on the ground, following OS break-in procedure. After that, you should be able to fine tune the high and low speed needles a little better. The low speed will likely need adjusting to get a really nice idle.

-Scott

Even though it may say that it's broken in at the factory, it's better to be safe than sorry. I will usually put 2-3 tanks of fuel through the engine (following the break-in procedure in the engine's manual) before I put it in the air. As Bubba said, a good break in is probably the biggest key to having a motor that will last a long time. OS engines are very reliable and will give you great life if you break them in properly. Just follow the manual. I've got an OS 46 FX that has over 500 flights on it and I've never had a lick of trouble with it. It starts on the first or second flip, and is still as strong as it was when I got it.

Ken

I'll say this about my OS engines. I have a 91 4-stroke that has well over 500 flights that was broken in using the recommended procedure and it just finally decided that it needed all of the tiny little "o" rings replaced in the carb. I have done that and she is back to purring like a kitten again. This engine resides in a 4* 60 and on the stock 14 ounce tank will give me an easy 20 minutes of half throttle flying and more if I shoot touch and goes for the whole tank.

I've had 3 46AX's that were sold with the planes and I see all of them allot at the field and all 3 continue to run well and 2 of them are are two different H9 Twist's and are flown rather hard. Treat 'em right and they will reqard you with tons of hours of flying, run them too lean and they will eat themselves alive quick

What's the best way to break the engine in on the ground? I assume the engine is mounted in the plane with the prop installed. I've seen people use wing stakes (is that the term?) that are placed in the ground and then rest against the leading edge of the wing so the plane does not move when power is applied. As I've have never broken a plane engine in, any help is appreciated.

If the motor is mounted on the plane it's fairly easy to restrain the plane. A piece of rope and a screwdriver are all that you need. Tie a piece of rope around the tail of the plane, make sure that it goes around the front of the horizontal and vertical stabilizers, and tie that to the screwdriver. Push the screwdriver into the ground to hold the plane while the motor is running. This will restrain your plane with no problems. Even though the plane is held down, you still want to be careful
around the propeller, see diagram.

Hope this helps

Ken

How to break in an ABC type engine causes more controversy and arguments than just about any other subject and about the only thing that's agreed on is to use more oil (especially some castor) and never to run it too lean.

My personal preference is to set the mixture quite rich to the point where the engine is just breaking between a 4 stroke and 2 stroke sound. This is basically what nearly all manuals recommend depending on how you want to interpret them. Rossi calls it "greasy exhaust" for instance but any setting that's very rich but not quite into a 4 stroke is fine too. Run it at this rich setting for about 20 minutes (a couple of tanks) then start leaning it out slowly over the next one or two tanks and it should be ready to have the idle mix set and go flying. Avoid leaning out to peak revs though, keep it at least 500 below peak revs.

Now the arguments will start

You hit the nail on the head with this comment!!

That's why I recommend to follow the manufacturer's instructions for break-in of an engine. If you mess the engine doing it this way then the warrenty will take care of it.

Ken

MAKE SURE the prop is installed! If it isn't, the engine will die within 10 seconds. (It would also be kinda hard to start without a prop ). I just used the OS manual instructions to break in my Nexstar. Good luck!