What Am I Missing Here?????
 

I'm helping a newcomer with his first trainer build/set-up. He bought an OS .46AX.

This is a non-ringed engine... but the manual describes a ringed break-in (first two tanks rich, etc.) At first I dismissed that, then got to thinking; with all the bizarre linings, platings, coatings, etc., OS has been "experimenting" with in the past ten years, who knows what this thing really needs??? I haven't messed with a new-production OS small two stroke in quite some time.

I'm a firm believer in bench break-in, and I'm inclined to do this one like an ABC/ABN.

Does anyone know any compelling reason NOT to do that? And, please... don't tell me "because the instructions said so".

And what's with that blocky chunk disguised as a muffler??? Jeez... that thing looks it came off the back of a '55 Cadillac...:eek:

RE: What Am I Missing Here?????
 

Go with the ABC/N break-in procedure. Run it only SLIGHTLY rich for a couple of tanks on the ground. When it will hold an idle, put it in the plane, lean it out, and fly it.

Dr.1

RE: What Am I Missing Here?????
 

ABC engines should be broken in rich, but usually not as rich as a ringed engine. However OS does not fit their ABN engines as tight as others so a very rich mixture may not do any harm and would help keep it cool. I would simply follow the manual.

RE: What Am I Missing Here?????
 

That is an OS for ya. HEHE
I would break it in the way they recommend (I am not sure if it would handle a break in like a real abc engine). If it fails send it back and get a real ABC engine from a different manuf.

RE: What Am I Missing Here?????
 

How rich are you talking.[X(] I have never broke an ABC moter in rich, but just a couple clicks richer than actual flying or driving, and run it the way it will be used (very tight little Rossi and Picco .12 competition car engines). I use a heat gun to preheat the clyinder the first few start ups and get the engine to operating temp as fast as possible. If you run a tight abc engine rich, you are just scrubbing the tight pinch away and putting one hell of a strain on the connecting rod. I have a Rossi .12 that has a tight pinch at tdc after 3 gallons.

RE: What Am I Missing Here?????
 

SLIGHTLY rich. Only 3-4 clicks off totally leaned out. ABC/N engines are machined with a smaller taper at the top of the cylinder. If the cylinder doesn't get up to operating temperature, it will wear excessively, lowering the power and shortening the life of the engine.

Dr.1

RE: What Am I Missing Here?????
 

Don't go rich enough to "4-cycle" it (fire every other revolution).

RE: What Am I Missing Here?????
 

If you follow OS instructions for the LA series you end up breaking it in the four cycle mode. I have seen a couple or three broken in this way, no problem. Also many C/L stunters break in and even fly engines such as LA and TT GP in a four cycle mode.

RE: What Am I Missing Here?????
 

Thank you. Its amazing how, even with places like RCU, that this fact just isn't often acknowledged.

Actually, what I was looking for was whether or not OS tried yet another "miracle" coating/lining/plating on this thing, that might require different handling. Apparently not.

Thanks, guys... even ya'll who said "follow the manual"...;)

RE: What Am I Missing Here?????
 

I did (with an ABC, not an OS) and really rich, stinking slobbering 4 stroke rich right from the first time it started just to see what would happen. After 45 minutes like that the piston didn't even look like it had been run and all the original pinch was still there. The piston didn't look quite as good after I did some more running at a much leaner setting (about 1000 or so below peak) but it wasn't really harmed. It lost some pinch though.

RE: What Am I Missing Here?????
 

It's the piston that wears not the cylinder. The only good reason for bringing it up to temp is when the pinch is so tight that it puts too much strain on the rod. The engine will improve till the pinch is almost gone. It will last most of its life that way. I have seen people sell there engines because the pinch is gone. Actually its still there, you just cannot feel it till you remove the glow plug.

RE: What Am I Missing Here?????
 

Sport,

Your first statement is correct.

Dr.1

RE: What Am I Missing Here?????
 

So OS and all of those C/L guys don't know what they are doing?

RE: What Am I Missing Here?????
 

I know what's worked for me for many, many years.

Dr.1

RE: What Am I Missing Here?????
 

I allways make sure the engines reaches 200-210 deg's F.

RE: What Am I Missing Here?????
 

Sure that works. You can also break in a ringed engine without four cycling it. You can do lots of things and still get good results. The question is what will give the most consistant results. With so much change in materials and fits, and especially considering OS's past pealing problems, I would go with their recomendation. That would be a four cycle break in.

http://www.osengines.com/manuals/46ax-manual.pdf

RE: What Am I Missing Here?????
 

--------------


Like you, I'd go with the rich two-cycle break-in as described by Dar in his posted procedure. But, if asked by Hobby Services, I'd say that I followed the directions to a "T". <G>

I don't know how true it is, but I've read elsewhere that the AX muffler is the result of lots of research. Of course, I'm just repeating what I have read.

RE: What Am I Missing Here?????
 

Steve,


Look in the [link=http://www.osengines.com/faq/product-faq.html#q2]OS web site[/link].

...And at [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]this RCU thread[/link].


As Brian said, your OS will probably not sustain any measurable damage from any technique, but as [link=http://www.rcuniverse.com/forum/m_3402107/tm.htm]Dr. Nitro found[/link] (post #23), it may not last very long anyway.

RE: What Am I Missing Here?????
 

With ABC/N engines, I have run the whole spectrum of break-in -- from slobbery rich progressive runs starting at idle -- to rich 2-cycle short full-throttle thermal sequences. Not a single one showed any significant ill effects. This is very definately not the case with steel-sleeve lapped mehanite piston types & ringed engines, but the ABC/N's just don't seem to care. At one time I worried about this, but I don't any more -- in fact now I just go flying with them -- not hard at first, but just using them comfortably. Still no ill effects.

RE: What Am I Missing Here?????
 

I've set up perhaps half a dozen of these for guys, some on brand new "never-been-run-until-it-was-at-the-field-for-its-maiden" engines.

They are one of the most user friendly engines known to mankind. Once the slow run and main are set, just use them and they'll last and last and never need setting again (within reason). They don't have a great deal of pinch new yet they are one of the most powerful sport .46s available.

Don't worry about special breaking in procedures - just avoid lean runs, take it a little easy (a couple of clicks rich) for the first three or four tanks and fly.

Newbies that turn up to the field with AX .46s learn to fly really quickly, because they don't waste time dorking around with their engines.

It makes me laugh when all the doom and gloom merchants start talking about the piston and rod wearing out when the main is set a little too rich. I hope these guys fly at full throttle all the time and never ease off to idle when they land. Imagine that piston wear on final approach! Ooohh ahhh!

RE: What Am I Missing Here?????
 

Harry,
Some ABC motors are tight enough to seriously strain the rod if not destroy the rod if idled or ran to rich when brandnew, if the engine is not run hot enough.[>:] NO I am not talking about OS, they don't even make a real abc engine other than a couple car and boat motors which are far from any kind of serious performance engine engine.:D I was not sure how durable OS's tencnicaly advanced painted on clynder (i mean cheap imiatation substitute for the real thing) is.:D:D Maybe if you ever venture to the wild side and pick up your self a real performance engine, I don't care if it is for a plane, car or boat you would understand.:D:D

RE: What Am I Missing Here?????
 

What amuses me is that anyone who's actually run them rich (when new) all report no ill affects and yet it's the ones who wouldn't dare do it because of something they've read that are the most vocal that it'll cause damage. If it were true then wouldn't you expect every manufacturer to have in big bold red letters "DO NOT EVER RUN RICH!" at the top of their instruction manual?

I agree with britbrat that ABx's just don't seem to care so long as they're not run lean. That's why Dar's ever-referenced link to the one-and-only way works...the engine itself could care less.

RE: What Am I Missing Here?????
 

Downunder
Some of the engines that I am referencing, like a Rossi .12 Outlaw, or a Picco .26 Outlaw (car and Truck engines that put out 40,000 + Rpm's), are so tight, that if you do not preheat them you will have one hell of a time. They will get stuck on Top Deap Center so bad that you have to use a pliers to get them of. If you try to run these tight engines like that you are going bust something. The masnufactures of these high performance engines recommend a heat gun, when breaking in. Once you preheat them, they start fairly easy. You only preheat them for the first few tanks. I have never seen a tight OS, then again I have never seen a real competition engine from OS either. Some of there car engines with the painted on liner are junk after a gallon or two, while a good motor like a Rossi or a Picco are only considered broke in after 2 or three gallons.:D

I use the same break in for all my ABC engines, plane, boat, car, and I don't use OS.:D:D

RE: What Am I Missing Here?????
 

I agree that some of the other than ABC engines really are not critical of rich running, which is probably how the LA series was designed - non critically, for use by beginners.

RE: What Am I Missing Here?????
 

Motorman, why are you talking about high performance car engines when the rest of us are referring to sport aircraft engines; specifically the OS AX .46?

Tell me, have you ever seen an ABC or ABN aircraft engine destroy itself when the engine entered into a destructive rich transition when new? That is...., actually *seen* one do this as opposed to reading about it on some forum?

How do you apply the same break in procedure to a car as you do a plane? Do you put props on all your engines to break them in? Or do you put all your engines in a car before they go into boats or planes?

No-one is disagreeing with you regarding the tightness of some ABC engines. No-one is saying "break in all engines blubbery rich". For example, I have a Jett .90 which was very tight when new and is still tight 15-20 hours later. I broke it in according to Jett's instructions, which I think are good for any ABC engine. In summary, they say "run it at the same revs it will do in use but with a slightly lighter load, running rich".

This engine has to idle for perhaps a full minute or two every time I ease off, approach, land and taxi back to the pits. It is not very hot when it is shut down. It does not destroy itself during this routine even though it is extremely tight and is running at a temperature much lower than it would even running at a full blubbery rich setting at full throttle.

The only thing I've seen destroy a good engine is a lean run.