The XLS .25 Combat Engine

Tell us what you do to get the best performance from your engines.

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David Drowns
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Re: The XLS .25 Combat Engine

Post by David Drowns »

I love it. The first production flight report. :D That's what I was expecting from what we saw of the test engine. Don't know about the shutting down problem. Mine shut down just fine. I know the GMS always had that problem but a little rtv sealer always seemed to do the trick. Did you opt for the rear needle screw position? I left mine up front.
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gsjames
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Re: The XLS .25 Combat Engine

Post by gsjames »

Check the setting of the idle bleed screw. If it is open too far, it is like having the carb barrel cracked a bit.
Gary James
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lightning
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Re: The XLS .25 Combat Engine

Post by lightning »

gsjames wrote:Check the setting of the idle bleed screw. If it is open too far, it is like having the carb barrel cracked a bit.
Thanks Gary, I'll give it a shot next time out (which may be tomorrow).
David, like you I left the needle on the carb for now.
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

Well I ran the .25 today in between downpours whith the 8 x 3 and needle up front.
It hit 21,540 RPMs I do not want to take it any higher with this prop so the next runs
will be with the 9 X 4 and every thing else the same but upping the nitro as I go,
I will let you know my high RPMs Tomorrow.
Does anyone else have Numbers ( RPM ) with the 9 X 4 or 9 X 5 props ?

Some of you will hit higher numbers than me as my .25 had a little pinch at T.D.C.
but did not lock up like a lot of magnums do. So my engine was at the low end of the
tolerance being a looser fit.

Keith this one shuts down once the Throttle closes..
Don Holmes RCCA #957
Mid Atlantic Combat
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lightning
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Re: The XLS .25 Combat Engine

Post by lightning »

Don Holmes wrote: Keith this one shuts down once the Throttle closes..
Hi Don, didn't occur to me when I first read Gary's comment about the idle screw - these motors are not an air bleed idle mixture, like the OS they are a separate fuel metering needle, so I don't think turning the screw in is the answer. That will simply lean out the idle.
Air leak must be elsewhere. I might try a fatter "O"-ring under the carb.
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

Hi Keith. You are right there is no air bleed screw but there is a low speed needle and a high speed needle. Now in the past ASP and Magnum have been using O rings a little to0 small and that allowed air to leak in and I would replace these O rings with Mugen Seiki S3 O-rings and the leak would go away.
This is a TWEAK I always do to my .15 .25 and.28 ASP and Magnum Engines But it makes the needle very tight.
Don Holmes RCCA #957
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lightning
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Re: The XLS .25 Combat Engine

Post by lightning »

Don Holmes wrote:Hi Keith. You are right there is no air bleed screw but there is a low speed needle and a high speed needle. Now in the past ASP and Magnum have been using O rings a little to small and that allowed air to leak in and I would replace these O rings with Mugen Seiki S3 O-rings and the leak would go away.
This is a TWEAK I always do to my .15 .25 and.28 ASP and Magnum Engines But it makes the needle
very tight.
Don, you are talking about the "O" ring on the high speed needle - right? On my Magnum 15s I replaced them with the OS part from my local hobby shop - have not done that with the 25 yet. Might be a good place to try first.
Where do you get the Mugen Seiki O-rings?
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

I get these O rings at Tower hobbies part #MUGC4121
But these are tight and the needle is hard to turn you my want to use the O S o rings if they work good for you on the .15 stay with them.
Yes the high speed needle. here is another Tweak we do, Place a bit of large diameter fuel tubing over the low speed screw

See http://www.midatlanticcombat.com/
Don Holmes RCCA #957
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lightning
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Re: The XLS .25 Combat Engine

Post by lightning »

Don Holmes wrote: Yes the high speed needle. here is another Tweak we do, Place a bit of large diameter fuel tubing over the low speed screw

See http://www.midatlanticcombat.com/
You've got me totally confused with this - just like the OS 25FX, the low speed screw is flush with the end of the carb barrel at the throttle crank end. I don't see any way to put tubing over it :?: :?:
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

lightning wrote:
Don Holmes wrote: Yes the high speed needle. here is another Tweak we do, Place a bit of large diameter fuel tubing over the low speed screw

See http://www.midatlanticcombat.com/
You've got me totally confused with this - just like the OS 25FX, the low speed screw is flush with the end of the carb barrel at the throttle crank end. I don't see any way to put tubing over it :?: :?:
We did this with the old .25s and I did it with my .52XLS 4S, where the nut locks down the throttle arm you would put rubber tub over the nut, This would seal and lock in the low speed neddle. I have found no need to do it with this .25XLS
but if I get air leaks or the low speed needle starts backing out it would be something to look into.
Do you see how if you put the tub over the locknut it would lock the screw in and seal air leaks
look at the photo in the link, under Magnum engines and click photo for close up
Don Holmes RCCA #957
Mid Atlantic Combat
Yankee Samurai
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Re: The XLS .25 Combat Engine

Post by Yankee Samurai »

A friend of mine was breaking in his new Magnum XLS .25 on Friday. At 18,500 RPM the connecting rod exploded, hope this is an isolated incidence.
Randy Shiosaki
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lightning
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Re: The XLS .25 Combat Engine

Post by lightning »

Yankee Samurai wrote:A friend of mine was breaking in his new Magnum XLS .25 on Friday. At 18,500 RPM the connecting rod exploded, hope this is an isolated incidence.
Wow :!: I am surprised.
First thing I did with mine was to take it apart to have a look at the design (and make sure there was no junk left inside). Seemed to me the connecting rod looked more substantial than the 25FX ones. Of course a visual check does not compare materials.
The check for junk was based on experiences with other Chinese engines (aka ASP) :shock: The Magnum was clean as a whistle.

I pinched my Magnum briefly up to 18,000 rpms but after 3 tanks launched it slightly rich at 17,500. From the sound of it in the air it was running well over 20K. So much so that I throttled back when diving. It does only have about 30 mins run time so far :!:
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David Drowns
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Re: The XLS .25 Combat Engine

Post by David Drowns »

The test engine we got to try was getting 19,300 rpm's on the ground with a Mouse can and ran solid in the air. They're sure to take care of you for something like that. They do want to do business with us. It's hard to miss their intent when you read the operating instructions.

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David Drowns
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

Sorry to hear about the blown engine and at only 18,500 RPMs...

Well I put the 10 X 3 APC on and let it rip still on the wood block and she was doing 15,760 RPMs
with the stock muffler no baffle. That is all I need to whip up on some locals around here. But I want
to build a new plane for these engines. A friend is cutting a new war bird and I still have, in the box,
a Bullet Proof P-47 2948
Don Holmes RCCA #957
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lightning
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Re: The XLS .25 Combat Engine

Post by lightning »

Got another 3 tanks through my engine today!
All done in flight on a Flat-Bat!
Last flight I leaned it a little closer to peaked. It was doing 17,950rpms briefly peaked and I launched at 17,700rpms.
MA 8x5 prop. 10% Powermaster fuel with an extra 2% of castor oil added.
That plane was screaming! Without another plane in the air for comparison it's tough to judge, but I think was every bit as fast as ANY of my OS powered Phenceposts. And this is with a stock muffler (minus the baffle)
Will be interesting to see what it does with 15% fuel.
Engine has now lost that pinch at TDC so I think it's pretty close to broken in.
If these things have the reliability of the OS they are going to be unbeatable!
Still can't get it to quit cleanly though, even with fuel tubing over the needle. It does eventually die, but takes maybe 30 seconds.
Playing with the idle mixture screw made no difference.
I suspect I need to pull the carb and add a little gasket cement around the "O" ring.
Keith Jones
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