I want to "break-in" my new OS 61 FX Glo Engine according to the manufacturer's instructions. But the whole procedure is based on switching back and forth between "slow four cycle" operation and higher speed "two cycle" operation. I don't know how to recognize "four cycle" operation.

I'm very much a beginner, having run only a Magnum XLS 46 for a couple of hours. I've done the high speed needle adjustment many times, tuning for maximum RPM then enrichening it enough to reduce the RPM by 200-300. But I think all of that is at "two cycle" operation.

Any advice for me on how to recognize "4 cycle" operation? I have the engine set up on a test stand (sort of) and am trying to decide what to do next. Out of curiosity, and without touching the needle valves, I hit it with the electric starter and it started right up. AMAZING!! But I only ran it for about 4 seconds, long enough to shut it down. Omega fuel, 10% nitro, 17% oil plus a little added castor oil.

Thanks for any help.

Frank

open the needle further, until it starts missing beats. That is four-cycle mode.

The present day Schnurle ported two stroke glow engines have a much broader two stroke rpm range relative to four stroking rpm range.

Fifty years ago the baffled piston design engines had a broad 4 cycling range compared with 2 stroking. The preferred tuning point on the ground for these engines was at the top of the four stroke range. When the plane took to the air, the engine would unload into the two stroke range and run perfectly and hopefully not too lean.

When 4 stroking the exhaust sound is somewhat like a Harley, a deeper rumbling sound. If you hear the usual higher pitched scream of 2 stroking (which you must know given that you've done a couple of hours with the Magnum) then keep opening (richening) the high speed needle and listen to the revs decrease. Fairly soon you'll be hearing some misfiring so keep opening the needle until all you hear is the misfiring and none of the higher pitch. It mightn't be a bad idea if you tried it with the Magnum first just to get familiar with it.

Don't break the engine in in 4 cycle mode!!!!!!!!!!!

There have been several threads on here about it...four cycling in the breaking in period doesn't allow for proper liner expansion due to low temperature, and it will end not smoothing the surfaces but in a premature wear..loss of compression...

The engine should be broken in with a smaller prop allowing it to run at a higher rpm, still in 2 stroke operation, running rich but not four cycling...the small prop allow the engine to turn high rpms without higher loads.

Dar Zeelon wrote a complete breacking in procedure for ABC/ABN that works the best, do a search here.

Jorge

Thanks for the advice, guys.

Must I do that process (richen the high speed needle) at full throttle (WOT) while listening for the "Harley Rumble" or can I do it at mid-throttle (or less)?

I will try it with the Magnum 46, just hope I don't screw up a nicely running engine. I should probably run down to a local Harley shop and listen to some of those engines!!

Frank

Breaking in is usually done at WOT,

Take a look a this thread....this describes a proper break-in procedure!! [link=http://www.rcuniverse.com/forum/Tapered-Bore_Engine_Break-in_-_Upgraded/m_1850473/tm.htm]Tapered bore breaking in by Dar Zeelon[/link]

Jorge

Jorge

Thanks for the advice.

I'd like to use the manufacturer's (OS) instructions for the break-in procedure. Those instructions have us start with 1 minute at 4-cycle, then alternate between 10 seconds at 2-cycle and 10 seconds at 4-cycle for the balance of the tank. So, as you advise, we're not really breaking it in at "COLD" 4-cycle temperatures but rather alternating between hot and cool temperatures.

My problem is that I don't know how to recognize 4-cycle operation.

Maybe I'll learn to recognize it tomorrow!!

Frank

You must break in your engine with the throttle wide open and vary the speed with the needle valve.

If it were my engine, I would not allow it to four-cycle at all. A rich two cycle can be maintained without overheating the engine. This type of engine needs to run warm right away to allow the upper cylinder to expand to normal size and not wear the piston prematurely.

If you run it at a cold fourcycle for the first minute, it may loosen the fit of the piston and liner, this is exactly what you don't want to happen if you intend to have a powerful, long lasting, engine after break-in.
You would want to run a ringed or iron piston engine very rich right from the start, but not this one.

Some people says that sometimes O.S instructions are often leading premature wear to the engines so they can sell more engines and spares...

I hope you read the thread and understand the reasons why you should not run the engine in a 4 cycling mode at all....as said in the previus post, the liner is tappered in the highest part so it achieves a better compression, but it is intended to expand at normal operating temperatures and , if the tapper does not expand, what you will get is wear, not mating the surfaces....

Better results have been obtained from that breaking in procedure rather than the described in the O.S manual.

Think of it...and also you will see that Dubb Jett Recomends the same procedure on his engines....I think you should know Jett engines...

Anyway, it's your engine, and is up to you...

Jorge,

NO, NO, Jorge. I have not meant to challenge you or your much appreciated advice. It is simply that I start from a position of complete ignorance on this matter and usually follow the advice of the people who produce the device in question. I do choose not to believe that the manufacturer (OS) would intentionally sacrifice his reputation on the altar or selling more engines and spares. I also believe that in this case more thought is required!!

I will study the article by Dar Zeelon (recommended by others also) in greater depth and will most likely follow that guidance. Thank you so very, very much for taking the time and having the patience to help me. I now understand more about this very important aspect of getting the best performance from an expensive part of a model airplane.

Frank Phelps
Grants Pass, Oregon

Quote:

ORIGINAL: estradajae

Dar Zeelon wrote a complete break-in in procedure for ABC/ABN that works the best, do a search here.

Thanks, Jorge.


Frank,


If you want to follow this break-in thread, it is [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]right here[/link]!

Even "Hobby Services", the OS importer for the USA, [link=http://osengines.com/faq/product-faq.html#q2]agrees[/link] the procedure OS describe in the manual is flawed... OS don't seem to 'second guess' their US rep, but for some reason seem reluctant to rewrite their manual...

But this is the way OS usually work... Never admit there is a problem and it will eventually go away...

Frank,
You should get a hold of someone in the club to help you with this. Send me a PM and I'll let you know who in the club has a lot of experience with OS engines. If you need to do this in the next few days I may be free to help. George

Dar Zeelon

Thank you very much for your current response to my query, and also for your efforts 4 years ago in writing that very elucidating thesis on ABN engine break-in. I will use the method described there-in. It appears that this case justifies an exception to my long-standing tradition of accepting the recommendations of a manufacturer over the advice of other specialists.

Frank Phelps
Grants Pass, OR

I think if you you go with Dars or OSs method you will probably end up with a nice running engine. If you look at the manual it says to run the engine with the throttle fully open for a minute rich and then alternate 4c and 2 c at 10 sec intervals. Now to my mind this doesnt mean run it so rich it doesnt even warm up but to my way of thinking its more a heat cycling method instead of running it 2c and then shutting it down to cool off. Now if the conrod was about to explode with this initial rich running why would all the 2 s engines I have say to slowly warm the engine up instead of immediately go to full throttle 2s running? Now I have my crash helmet on and am ready to be shot down. Cheers the pope

Nah...I won't shoot you down pope...not after I ran a new ABC slobbering rich for 45 minutes to see what would happen to it. Didn't affect it in the slightest...still had the same pinch as straight out of the box but got a bit oily inside . One thing I learned from that experiment though is that no matter how well you do a hands on test of something...if it doesn't conform to the Myth then it won't be accepted .

Thanks Downunder Im glad your on my side, its nice to know youve got my back when Dar comes a shooten from the lip.[:-] Us aussies gota stick together. Cheers the pope

How true that is[X(]

However, an experiment that is done gives results.....good or bad, and those that choose to listen will benefit from your work. Sometimes those that are listening do not always choose to post a response.

Richard

Second that ... Myths are stardard statments that can not be stopped,
Rich

Wait, the OS engine is a ringed engine.... Nobody has made mention of this!!!!! You CAN run a RINGED engine rich... I almost exclusively fly OS engines and I have always broke them in the way OS recommends, all my engines are hand started, and all usually start on the first flip. The engines that you do not run in a rich 4 stroke manner are the non-ringed ABC engines like a dub jett... but the jett engines and the OS ringed engines are two different beast all together....I can explain further if interested, but take it from an OS man, the OS break-in is just fine.

Most small sized O.S engines are not ringed....

FX series from 25 to 61 are ABN.. 46AX, 55AX, 75AX are ABN...

91FX, 120AX and the bigger and 4 strokers are all ringed....

Ok, I Stand corrected[8D].... I own the larger 2 strokes, if the smaller one's don't have a ring then by all means DO NOT run them 4 cycle rich!!!!!!

Quote:

ORIGINAL: Fishin Geezer

I want to "break-in" my new OS.61FX Glow Engine according to the manufacturer's instructions...

Quote:

ORIGINAL: Mugekidd

Wait, the OS engine is a ringed engine...

MugenKidd,


Say what??? That is completely incorrect!

The OS.61FX engine is a non-ring ABN engine.


It is better to check your facts, before offering your input.

Also, what is the highest total time that any OS engine that you have?


Using the method recommended in the manual, they typically don't last for as long as you might expect.


..........I see I was already beaten to it...

I already admitted my error!! I have 3 160 fx's that I fly weekly... btw why don't you check the entire thread before you offer your input

MugenKidd,



Please read the last line in my post...

It was open for editing and I went up for lunch...
I sent it upon returning to my PC and only afterward I noticed estradajae has posted, so I entered that line...