....

i know... i tested today a 11x7 and i really like it.... fast, a lot of vertical....and not bad for the distance from the ground to the propeller. I know is hard to find the right answer, most of the people says lets try it and thats it.

I'm saying is that there must be alot more manuals out there that need to be corrected. Think of the engines that you could be saving.

O.S. and now NovaRossi are done, we can submit one when we find the error and you can "Redline" it for content.

I don't know why are you having prop clearance problems with your Sukhoi with a 12x6, I have a 13 on it and never broke a prop, (blackhorse sukhoi which is the same plane)...

cause it jumps like a rabbit!!!

Guys,


We're drifting off-topic here...

This thread discusses the right way to break-in a tapered-bore engine - not propping an OS.55AX...


BW,


I can only tell NovaRossi over these pages, that they should read the technique illustrated here...

But I am not sure... I have seen Italian written documents, that have terms a normal English speaker will fail to comprehend.


As far as I'm concerned, they might read it and say: "That's exactly what we meant"...

Far be it for me to always agree with Dar, however I have been using the break-in method that he talks about for years and my engines are very, very strong. Even my “propped� ducted fan engines still have pinch at the top and the con-rods are tight after countless gallons of high rpm abuse and three or four normal interval bearing changes. Same thing can be said of my OS and YS two stroke sport engines.

Running-in a tapered-bore engine slow, cold, and excessively rich in many cases leads to reduce power potential and service life. Some guys run them in cold and of course a great majority of the engines run afterwards, yet they have no basis of comparison so they are content with the engine’s anemic performance.

Many times guys have said to me, “Is that only a XX size engine?�, “is that engine stock?� or “why is your engine so much stronger than mine, I’m running the same setup as yours�. I have a look at their engine and it has less compression (pinch), excessive rod play and their engine is much newer. The guys swear they were never run lean. The differences? How they were broken-in.

Why do some manufactures recommend the cold, drowned in fuel, four stroking method break-in?
They probably figure it’s safer than an engine ran too lean, for that will have a much greater chance of damage than one that’s too rich. In other words it’s better to error to the side of less engines totally “lunched� and more engine still running, but just OK.

<span class="Apple-style-span" style="font-family: Geneva, Verdana, sans-serif; font-size: 15px; ">Is this the thread of doom or what?</span><!StartFragment><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US">It now spans 6 years in these pages and probably much more than that if Dar counted in all the lead-up to it.<o></o></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US"><o></o></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US">For what its worth I agree with Dar on his method on extending the useful life, power and reliability of a tapered bore engine that uses a plated liner.<o></o></span><font class="Apple-style-span" face="Geneva, Verdana, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 15px;">
</span></font></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US">I have a good friend here in Oz that has been flying with MVVS engines since the 1970&rsquo;s, his background is in metallurgy and machining, and when I approached him about how to run in my MVVS his method almost mirrored Dar&rsquo;s.<o></o></span><font class="Apple-style-span" face="Geneva, Verdana, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 15px;">
</span></font></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US">To sum up, he has always used castor and the only time he varied to synthetic oil it washed the varnish off an old piston/liner assembly and rendered it unusable.<o></o></span><font class="Apple-style-span" face="Geneva, Verdana, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 15px;">
</span></font></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US">And I was advised to run in my unused MVVS at speed, using his words &ldquo;like you mean it,&rdquo; otherwise you risk shouldering off the top of the piston. The insurance protection here is the higher percentage of oil used and the type.<o></o></span><font class="Apple-style-span" face="Geneva, Verdana, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 15px;">
</span></font></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US">Castor will not flash off at the temperature that occur in our engines and is still the ultimate oil for our purposes.<o></o></span><font class="Apple-style-span" face="Geneva, Verdana, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 15px;">
</span></font></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US">The kicker is that my MVVS will be run in as a glow engine and then converted to diesel as soon as it has been, so I doubly want that &lsquo;pinch&rsquo; at TDC left in place.<o></o></span><font class="Apple-style-span" face="Geneva, Verdana, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 15px;">
</span></font></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US">Now I could choose any method that I wanted to in running it in and after much investigating I choose the one illustrated in post 1.<o></o></span><font class="Apple-style-span" face="Geneva, Verdana, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 15px;">
</span></font></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:Geneva;mso-ansi-language:EN-US">Cheers.</span><span lang="EN-AU"><o></o></span></p><!EndFragment>

http://www.rcuniverse.com/forum/m_1890371/tm.htm

Wouldn't more oil result in more exhaust residue which, leaving the combustion chamber and exhaust, would take heat along with it??

Who's "they"? The folks at Weston UK attempting to sell products? Or is "they" a third party of some kind?

Extra oil does take heat with it. I have no problem cleaning the Castor Carbon off in the Crock Pot. I just did a Decarboning on one of my Tower .75 last night. I would rather error on a little castor content than chance running striaght Synthetic. The straight synthetic leaves next to no rust protection, and a lean run can kill the engine. I also break in True ABC engines at WOT sta just a little rich. I preheat them to ease the stress on the rod the first run. I have yet to have a engien loose its pinch. I am just finishing decarboning a Tower .75 that has many many gallons throug it, and the piston/sleeve look like brand new. This engine still has so much pinche that it squeaks when cold. Did I mention that the engine has no noticable rust in it at all!

This is why I'm always leary of someone grading their own homework.

I just purchased two Thunder Tiger GP-28s. These are ABN tapered bore engines with bushings and air-bleed carbs. The directions for break in from Thunder Tiger say to use fuel containing 25% castor oil and break them in at full throttle in a rich 2-stroke setting. Hmmmm.... sounds familiar.

Well that's fine...

I'm quite surprised that this thread never seems to end. But every now and then there are odd things popping and the thread deserves to live on. Here for instance is someone making an instructional video and setting a really bad example; [link=http://www.youtube.com/watch?v=MUty04SmYJA&feature=related]Don't try this at home[/link]

Mr Cox,


This person seems to make virtually all mistakes... Like idling a break-in, for instance...

It truly is a bad example... so why give it any airtime... There are people out there, who may assume the method is correct... It's on U-tube; ain't it?!

I try not to re-educate the people who are not willing to learn, or to stubburn to change. I have yet to have an ABC engine that ever looses it's pinch. My Tower engine that I am putting back together currently starts pushing the sleeve out when there is still about 1/4" stroke left, and that is after close to 20 gallons, and I break them in WOT.

Hello,

I need some serious help! I followed the procedure indicated at the beginning of this post and I was still able to ruin my piston & sleeve... I know that because my pinch at TDC without the plug is quite reduced. So, I have a Magnum 91 xls and I added 60ml of castor oil to 1 liter of 15% nitro with 18% blend oil as a baseline. I think that the fuel is o.k. I mounted the engine on a test bench. It seems that during some instances the engine overheated during the break in without any changes on the high speed needle valve, at what point I stopped the engine or made it more rich. Before the first run, I used my heat gun to pre-heat the engine. I started with 1 minute run and let the engine cool off completely before repeating this cycle 5 times. Then I ran 3 times the engine for 5 minutes leaning it somewhat while monitoring the temperature. I allowed the engine to completely cool off between the 5 minutes runs.
I ordered a new sleeve and piston and I would like to know if you could give me the following recommendations. Basically, I am looking for a procedure that will make the break in fool proof and protect the engine from the user

1) What propeller size to use for break in? Manual states 14X6 but in other posts, I have been told to use 12X7 or even 11X7. I plan to use my engine on a patriot XL.
2) How many turns should I open the high speed needle valve? Manual indicates 2 1/2 turns.
3) What RPM should I shoot for when I first start the engine?
4) What temperature should I have for target? 350 to 380 degrees Far ?
5) How long should I run the engine at first? 1 min or 30 seconds. The Magnum break in instructions recommend starting the engine at half throttle for the first minutes but I don't think it is what should be done.

Thank you for your help,

Le fou

Quote:

ORIGINAL: le fou

I need some serious help! I followed the procedure indicated at the beginning of this thread and I was still able to ruin my piston & sleeve... I know that because my pinch at TDC without the plug is quite reduced.

Le Fou,

It is not necessarily ruined...

Some engines are 'looser' than others and some are really loose.

Quote:

So, I have a Magnum .91XLS and I added 60ml of castor oil to 1 liter of 15% nitro with 18% blend oil as a baseline. I think that the fuel is OK I mounted the engine on a test bench. It seems that during some instances the engine overheated during the break in without any changes on the high speed needle valve, at what point I stopped the engine or made it more rich. Before the first run, I used my heat gun to pre-heat the engine. I started with 1 minute run and let the engine cool off completely before repeating this cycle 5 times. Then I ran 3 times the engine for 5 minutes leaning it somewhat while monitoring the temperature. I allowed the engine to completely cool off between the 5 minutes runs.

While breaking an engine in, one must not be oblivious to it overheating...
The mixture must be set ~500 RPM richer than peak. This should be monitored by an occasional quick pinch of the fuel-line.
If it causes the engine to speed-up, the setting is OK... If it sags, it is obviously too lean!

Quote:

I ordered a new sleeve and piston and I would like to know if you could give me the following recommendations. Basically, I am looking for a procedure that will make the break in fool proof and protect the engine from the user

1) What propeller size to use for break in? Manual states 14X6 but in other posts, I have been told to use 12X7 or even 11X7. I plan to use my engine on a patriot XL.
2) How many turns should I open the high speed needle valve? Manual indicates 2 1/2 turns.
3) What RPM should I shoot for when I first start the engine?
4) What temperature should I have for target? 350 to 380 degrees Far ?
5) How long should I run the engine at first? 1 min or 30 seconds. The Magnum break in instructions recommend starting the engine at half throttle for the first minutes but I don't think it is what should be done.

Nothing is fool-proof, because...

First, make sure you are not wasting your hard-earned cash on replacing good parts... Are the current sleeve and piston scored?
If not, the pinch does not have to be like new, just perceptible is enough for most engines.

1. For a .91 two-stroke engine, I would say a good break-in prop is a 12x8.
2. As many turns as it will take to have the engine running 500 RPM richer than peak - I don't know how much it is in your engine.
3. You should target an RPM level "500 RPM richer than peak" - peaking a new engine for a moment does no harm, so you can check.
4. You should target whatever temperature it is running at, "500 RPM richer than peak". I don't know what the exact °F value is, because this is not what I am looking for.
5. The first two-three runs I do are short, 20-30 seconds..., just to make sure no heat-soak takes place. Then full 5 minute tanks.

Le Fou,

I'd just go back to basics. I also have a Magnum .91 (in fact, I have two) and they both run very sweetly. I broke them in exactly per the manufacturer's directions which includes using a 14x6 prop. I think that a 12" prop might be too light a load... you want to put a load on the engine, but just not too heavy a load.

Do you have the manual? If not, I can send a .pdf copy to you,

Bob

Thank you for your help. I have a manual. Did you run the engine at half throttle per manufacturer's instruction? I thought that DarZeelon recommended not to do that.

I appreciate that you took the time to answer my questions,

Le fou

Quote:

ORIGINAL: le fou

...I have a manual. Did you run the engine at half throttle per manufacturer's instruction? I thought that DarZeelon recommended not to do that.

Le Fou,


Running the engine at half-throttle achieves nothing in a tapered-bore engine, because the engine will be very slow to reach its normal operating temperature.
It will probably do no damage, though...

But at the same time, I do not see what the manufacturer thinks can be achieved, in recommending that the customer does that...


Can you scan and post that page in the manual, or the whole thing?

le fou
Basically you did everything just about right by adding castor etc but you might have been caught out by the 2 1/2 turns suggested in the manual. That's just a guide and won't necessarily be correct, especially for the running in. Also, don't pay overdue attention to temperatures because if the mixture is set correctly then the temps will be what they will be. That said, I generally check head temps just for interest's sake and around 200F is fairly normal at the start of running in.

Running in should be done at full throttle and the first run should be with the mixture set rich enough to get a bit of 4 stroking for a minute or so then leaned just into a clean but rich 2 stroke. The revs will be much lower (probably ~1500-2000) than the ~500 from peak that Dar suggested because that's basically what you'd set the engine at after it's run in and you're going flying. For a first start I set the mixture where I can be fairly certain it's quite rich then lean out to the setting I want rather than have it scream its little heart out before richening it.

With all that said, I agree with Dar that most likely you haven't ruined your piston/liner unless it's scored or other visible damage. You mentioned it's still got some pinch without the plug and that's fine. Use the engine as it is and keep the new piston/liner set for when it eventually wears out.

It's all right here...
http://www.rcuniverse.com/forum/m_1890371/tm.htm


There is some good and bad information out there about break in proceedures for ABC type engines...... some info is a mixture of both. In general, a proceedure outline by an engine manufacturer should be followed as written.

Other engine manufacturers have their noted proceedures. The proceedures depend a lot on materials. Jett uses special alloy aluminum for all pistons, and all sleeves are TRUE chrome plated. For a Jett, that first minute of being rich does no damage to the piston or sleeve. It is no different than starting a Jett or any other ABC engine when cold and at idle. The proceedure outlined in the instructions and on the web site is very tried and true. Always follow it with a Jett engine, and the engine will run flawlessly.

Something of note. 'Taper bore' engines and AAC/ABC engines can be different. Some have a 'fixed' taper that does not change or changes unevenly. A well designed AAC/ABC engine has a taper and piston/sleeve fit that DOES change. Both the piston and sleeve change with temperature. When the engine is cold (at start) there is an interference that you can feel and hear turning over the engine... with a Jett, the audible 'squeek' is a good thing to hear! As soon as the engine starts (for sport engines, at idle) the engine begins to warm up, creating the appropriate fit between piston and sleeve. As you take the engine to full power and it reaches operating temperature, the fit becomes optimal, and you will hear the engine rpm increase to its full potential. If anything, you want it on the 'tight' side.

Isn't this where it all started? "The new and improved upgraded break-in thread"... ?

Hello,

Sorry for the late response, I did not have access to my computer for a while. I attached the manual to this email.

Thanks,

Le fou

BW,


Maybe the part of Bob Brassell's post that you should look at again is this:

"When Dub mentions "rich" in the break-in instructions, he has instructed that you have set needle valve initially at a very rich setting .... this to avoid any possibility of starting the engine lean. A Jett engine simply will not run blubbering rich (some other engines will) even with the glow plug driver on. It has to come up to a decent temperature and have a smooth mixture just to run stable. So by rich, he is stating that the engine is running, stable, with the glow driver on, clearly 'wet' sounding and clearly not peaked. This is, in most cases, a rich 2 cycle or just on a 4 cycle break."

Even they do not actually recommend you should four-cycle your two-stroke engine...


Le Fou,


Looking into this document; stage 4 of the procedure only tells you to run the engine at half-throttle for about a minute (apparently to prevent a heat-soak/spike), after which stage 5 tells you to go to full-power...

It is the later part of that stage which I cannot agree with... "Very rich" defines absolutely nothing!
It can be a rich two-cycle, or rich enough to four-cycle - there's no way to know what is meant by that term.


It seems this procedure, along with the 'sequel', in-flight continuation, which is very reminiscent of a ringed engine break-in procedure...
...Too reminiscent of this!


This procedure begins on page 3, with an explanation of the tapered-bore principle...
...But this is not carried on in the procedure itself; continuing, as if this engine is a ringed-piston model...

Also, please note the "Important" remark, at the top-right side of page 4...
A 30% RPM gain from 'unloading'??? Can you imagine propping your engine for 12K on the ground; only to have it spinning 15,600 RPM in flight?
Air entering the carburettor with higher force at speed???
Is someone suggesting Mach 0.7+ compressibility sets in at 100-200 kph flight speed???

The person who wrote this part of the manual, apparently had some 4-5 drinks too many, on an empty stomach; before taking on the task...


This is the reason I always suggest reading the manual and checking that it does not defy logic, before 'automatically' following it...
If in doubt; the procedure detailed in the beginning this thread, for ABC/AAC/ABN/Plasma Ceramic P+L engines, is as logically explained, as the character portrayed by Mr Leonard Nimoy in Star Trek possibly could.

I earlier gave the OS manual example; stating your should set your engine to four-cycle... and later directly contradicted by [link=http://osengines.com/faq/product-faq.html#q2]their Q&A[/link]...
The Magnum XL .91ARNV manual, in its break-in procedure; says many things, but actually says nothing...

I suggest following the info in this thread instead.


"Live long and prosper."