Does anyone have experience breaking in a new OS FS 1.20 E Surpass Engine? I usually use Saito 4 strokers, but decided to go OS. Nice looking engine starts easy but I find that the exhaust oil run-off is very dark, black-ish in colour. Is that normal during the breaking-in process? So far I ran the engineaccordingto the instructions; two full tanks running rich very rich and leaning out for 5 seconds every 10 seconds. Then I ran the engine very rich for a full tank that is three tanks at roughly 10 minutes each tank, so 30 minutes of initial breaking in, then I made a flight with the same rich mixture this time not so very rich. I find the run-off behind the exhaust is very dark, never had that with my Saito's.
Can anyone tell me if that is normal for OS? Looks like lots of carbon, could tis be just due to the rich mixture ( I do not think Methanol is a 'hydrocarbon fuel") or is it the carbon in the steel wearing in, or breaking down? I hope I am not damaging the engine.
By the way, the engine runs great and starts easy, but compared to my Saito's (F-100) the compression is not as high, it is good but not as high. On a cold Saito it is difficult to turn-over the prop in one continuous motion, you have to pause and let the pressure bleed off.
Looking out for some remarks and or suggestions.

Thanks.

PS: This is the airplane that the engine is in P-40:<br type="_moz" />

In my experiance with O.S 4 strokes, the black oil coming out of motor is ok. The O.S motor don't have the compression that the Saito's do, so again I would say its normal. To be honest I've found the Saito's to be far better then the O.S.

Thanks very much jay...... I agree the Saito's are a better engine, it's reassuring to know that the engine has not been damaged.

The black should clear up after you run it some

What type of fuel?With castor or 100% synth.

Sounds like you broke her in according to the manual. Good. The question of fuel/oil type and amount is a good one. Also, how about prop size and max rpm? Info on those all those things should allow everyone to come up with the best comments. And make sure all of your engine screws and the muffler connections are properly tightened. Sometimes that dark color can be metal from a loose muffler connection.

As a general comment based on about 8 OS 4-stokes and 6 Saitos, I don't like to see a dark or black exhaust and generally find that if I do, I'm running a bit too lean. That's using 20% total oil with 3% castor. So see if you can give us those #'s.

I think Augie11 hit the nail firmly on the head when he suggested loose muffler.Jez', vibrating alloy (even very slighty) makes an awful black mess.

David- do you use teflon tape on your muffler connections? I find it keeps things clean and also must help in keeping the muffler tight as I haven't lost any lately!

Thanks to all for your suggestions and comments; concerning the fuel it's "Cool Fuel" 15% 4 stroke, not sure how much castor is in the mix, I am running her at 7500 rpm using a 16x8 Master Airscrew at peak I am getting 8200, there are no loose muffler connections although I like the idea of the "Teflon"tape but concerned about the temp and its effect on the tape. Hope this helps with any conclusions.<div>Thanks again.</div>

Don't worry about the effect of temperature on the tape. It holds up just fine.
I'm not familiar with that brand of fuel. What is the total oil content?

I'm wondering if your prop selection, 16x8, isn't a little high for this engine. I run my 1.20 OS's on 15x8 or 16x6 and generally get around 9,000 rpm with clear exhaust. That's about 200-300 below max rpm. Just a thought.

I have a couple of the 1.20 and don't recall any black oil, gray for the first few tanks but it clears up pretty fast and then is clear as can be. Being as they have a header and the muffler connects to that if you have something loose I would think you would notice it? Tighten the header and muffler with the engine at running temp. There isn't any need for the tape but heat has no effect on it if you decide to use it. Mine all had the one piece muffler and there is no baffle to come loose to give the nasty dark gunk. They may have changed that sense I bought my last one?

PS-

OS recommends at least 18% total oil on the 1.2. There are those who disagree but that's one reason I stick to 18-20%. That dark exhaust can be metal but often it's just running too hot and the higher oil content is specified to minimize that.

Cool Power Four Stroke Fuel
Nitro Oil
<table cellspacing="1" cellpadding="0" border="0" width="100%" class="table"> <tbody> <tr bgcolor="#ffffff"> <td width="40%">

4-Stroke (standard)</p> </td> <td width="20%">

15%</p> </td> <td width="20%">

17%</p> </td> <td width="20%">

Ultra-High</p> </td> </tr> <tr bgcolor="#cccccc"> <td width="40%">

4-Stroke-MV</p> </td> <td width="20%">

15%</p> </td> <td width="20%">

18%</p> </td> <td width="20%">

Multi</p> </td> </tr> </tbody></table>

I try to avoid ever mentioning props but in this case the two props Augie mentioned are the two sizes I usually end up running on mine too, APCs. I still test props on these engines when they are in a new plane but I end up with one of these most the time.

Sorry people, the fuel make is not what I called it, the fuel make is "Cool Power" -15% nitro four stroke fuel, thanks w8ye for the correction, that's what I meant to say. The exhaust oil is also not black but grey, I use the word black-ish in colour but the run-off is actually grey. Last night I removed the cowl and checked the header and muffler; the muffler was slack. I tightened it and used some HTV black silicone on the threads to seal it, I will run it today and check the oil again to see if it is clear or less grey. I do not believe I am running the engine hot as the mixture is very rich, nearly 1000 rpm below the max, and correct the 16x8 prop is over-sized, I will use a 16x6 instead to help with better rpm's.<div>I am leaning on the assumption that the grey oil is wearing-in of the sleeve and ring and that it will go away eventually, I certainly hope so. Standing by further.</div>

I used High temperature silicone and no news after +50 flights... worked very well!!!! No leaks nor black cream around the exhaust or muffler.
The first tank I made while breaking made a little bit of black oil, from the secont up to now I barely realise about exhaust oil.
I'm running 18% oil + 10% nitro; propeller is APC 15x8 Pattern.
This engine is magnificent!!!!

I'm sure you're now on the right track, especially with that 16x6 and a solid muffler seal. Let us know how you make out with the exhaust oil color and also with the rpm on that prop. You're going to like that engine. While I wouldn't call it a powerhouse you'll find that since you took your time with the break in it will last...........forever !!

A 16x6 was certainly my old Surpass II's prop choice.

A 15 X 8 is also a standard prop for this engine

And the gray mater that blows out is just micro bits from things seating or smoothing out during break in. Nothing odd about that with any engine. If it's a lot then you usually look at the mufflers baffle plate if they have one. I never have the cowl on a plane if I'm using it for break in because you need to see if things are getting loose during the run up. New engines tend to do that. With Saitos it is usually the muffler/header that loosens up right away. It's just the heat expanding things and making them loose. Nothing odd about that either. 10-18 is just fine for fuel. I like the blended oils but I have friends that use nothing but the synthetics with good results.