The XLS .25 Combat Engine

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

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Don Holmes
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The XLS .25 Combat Engine

Post by Don Holmes »

I think this is going to be the hottest engine in combat.... I just started running in my .25 with the
8 X 3 prop first, 15 % nitro and 20 % oil. First run was 30 seconds. Second run with 9 X 4 60 seconds and it was taching at over 19,000 RPM's 3 turns out and not full throttle. when this engine runs in I think it will run in the 20,000 range.
P. S. Did not want to go full throttle as I though it may fly apart, It screamed
Don Holmes RCCA #957
Mid Atlantic Combat
draftman1
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Re: The XLS .25 Combat Engine

Post by draftman1 »

good to see that Don. thats what we have been saying all along, its a hot engine! :D
Andy Erwin
central CA
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

Yeah, But when you flip it over twice and it fires up on your stand and you go to open up the throttle
but get nervous close to full throttle ( I have never felt like that with small engines before )
Seeing is believing. Too bad you live so far away Andy we could do some COMBAT.
Maybe at the Nats one year.
See Ya
Don Holmes RCCA #957
Mid Atlantic Combat
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David Drowns
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Re: The XLS .25 Combat Engine

Post by David Drowns »

I picked up mine today. Good report Don. Now I'm getting excited about breakin this weekend. :D
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

Keep us updated on the running in Dave, and I will post more on mine latter.
My XLS .25 is taking the weekend off as I'm running my TT .40 Pro in a LA 40
Don Holmes RCCA #957
Mid Atlantic Combat
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David Drowns
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Re: The XLS .25 Combat Engine

Post by David Drowns »

Well...I ran the 8 x 3 prop first. I was hoping to go between 30 seconds and a minite...Asked "my assistant" to call out every 10 seconds....by the time I finally asked how long it had been she said "...1 minute" :roll: I shut it down right there. Let 'er cool down, ran the 9 x 4 about 2 minutes then took off for some family stuff. Got back this afternoon and ran a tank through real rich.

I was noticing how quiet it is. Then it hit me....this thing has a restrictor plate in the muffler.

Don, did you take yours out or change your pipe or something or just run the stock muffler that comes with it? With the
8 x 3 it went up to about 18.000 but running rich I'm pulling about 15,000 rpm's on the 9 x 4. I'm hoping that first run wasn't too long.

It is really smooth through the transition unlike the 15 XLS where some become erratic unless your at full throttle.
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

I have been told we want to get the RPM,s up right off the bat. So my first 2 runs are with the front half of the muffler only.
Sometimes I use a mousse can and pipe to run in.
I well be running in 2548 so restrictor plate in or out will depend on RPM,s at 14,500 will let you know more when I run this engine Tue.
Don Holmes RCCA #957
Mid Atlantic Combat
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

Well today I put the stock muffler on without a baffle, a ASP 10" X 3" prop.
This engine was turning 14,800 RPM,s and still not run in all the way.
I belive I will have to put the baffle back in to get it down to 14,500 RPM
as required in 2548 scale.
How is your's coming Dave ?
Andy do you have any yet ? Look just under you in the Nat. points

Thats all for now.
Don Holmes RCCA #957
Mid Atlantic Combat
draftman1
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Re: The XLS .25 Combat Engine

Post by draftman1 »

Hey Don, I havnt gotten one yet, I hope to really soon! yes I saw that, we are basicly neck and neck, how funny is that :D :D
Andy Erwin
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David Drowns
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Re: The XLS .25 Combat Engine

Post by David Drowns »

Well I didn't want to stir the pot before I found out. I noticed some play with the piston locked up at TDC of about 1-2 deg. It concerned me so I went back to where I bought it and the other new one was the same...The guy there said he'd find out from Mike Greenshields (Magnum product manager who had the test engine) and he'd get back to me. "Meanwhile" he said "keep running it in and we'll take care of you if there are any issues". So I ran another tank through on the test stand last night and all seems well. I couldn't tell you the RPM's because it was dark after finishing flight training with the students last night. More later when I have something to report.
Last edited by David Drowns on Tue Sep 28, 2010 8:02 pm, edited 1 time in total.
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

The Magnum XLS 46 engines are like that too. I had friends send them back saying they were bad but I run in my
XLS 46 and it is a screamer now, Just use 20 % oil at run in and it will be fine. and the good kind of fine!!
There are a few people around here that don't like Magnums, and there is play at DTC but that hasn't been
a problem and I have not found a bad XLS yet and the locked up feel is the pintch

Keep us posted
Last edited by Don Holmes on Tue Sep 28, 2010 8:16 pm, edited 2 times in total.
Don Holmes RCCA #957
Mid Atlantic Combat
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David Drowns
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Re: The XLS .25 Combat Engine

Post by David Drowns »

I feel better about it now. And I like the fact that I'll get an answer from the top as to what the play is all about. My next step is to get 'er mounted in an airplane and fly the snot out of it and get it good and broken in and see what she'll really do.
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lightning
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Re: The XLS .25 Combat Engine

Post by lightning »

If it ever quits raining here in Michigan I plan to get mine out and do some running.
I've got a 9x3 combat prop on it for break-in (Magnum says a 9x5 so it should rev a little higher!) and some 10% Nitro fuel with 2% extra castor added.
I'll do some running on the ground but I suspect I'll just want to get it in the air after maybe 3 or 4 tankfuls!
I will tach it to see how it's doing and will let you know.

I also noticed a little free play at TDC, more than new FXs. That has to be rod bearing or piston pin clearance.
Maybe it will tighten up once it gets hot.
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Don Holmes
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Re: The XLS .25 Combat Engine

Post by Don Holmes »

Well I wanted to see top end on this engine today so I put on the 8 X 3 prop running 10 % nitro and
18 % castor oil, stock muffler no baffle and doing the pintch on the fuel line I got 21,118 RPMs. It is on the 3rd tank of fuel and I would love to try some 30% nitro, but that will come after she is mounted in a plane and turning a 10 X 3 then we will see, I will go out and get in a mix so,
Watch your 6
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 »

The sun was finally shining today with temps in the mid 60s, so off to our field I went.
Three tanks through the Magnum on the ground with a MA 8x5 (my usual Open B prop), baffle removed from the muffler and 10% Nitro fuel with 2% extra Castor oil added.
Fired right up with minimal adjustment!
After 1 tank it pinched to 17,900 rpms but I richened it so it was running 17,500. (10% fuel remember!). Even when I briefly leaned it right out, the head temp never went over 250 degrees - much less than I expected with a new tight engine!
After 3 tanks it pinched to over 18K with the 8x5 which is as good as my BEST 25FX running 15% fuel and with the OS muffler stinger removed and the outlet enlarged.
After 3 tanks I said to H__l with this and launched it with the needle still ever so slightly rich.
Did that thing ever scream in the air! Sorry to disagree with you Randy, but that motor was NOT under increased load, it unloaded like crazy. I suspect it was hitting 20K+ in level flight.
With a 3lb 2oz Open plane it had absolutely unlimited vertical climb - better than any of my OS's.
Five 6oz tanks of fuel through it and there is still a slight "pinch" at TDC. I think it's breaking in just fine!
So, verdict so far is :-"Looking good".

One small issue (and it's the same on my 15s). There must be an air leak in the carb somewhere. It simply will not shut down with the barrel fully closed. On the ground it won't even shut down with my finger over the venturi, so there has to be air getting in somehow.
The carb was clamped down tight (to compress the O ring) before I tightened the clamping screw, so that should not be leaking.
Any suggestions??
Keith Jones
AMA CD #7601
Radio Control Club of Detroit
and proud member of the OGC
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