mustangman177

I though it was me having trouble adjusting my 55 AX until I found this post and started reading others with troubles.

I too have 2 of these engines, took out the baffles at the get-go. I too was having these problems as being discussed by others

I'm running Wildcat 10% nitro 18% oil. Using a 12 X 6 APC prop.

A friend of mine showed me a different way to adjust the low-end needle valve after watching me try to adjust it myself. His method was to open the throttle slightly above idle to maybe a 1/4 throttle setting and then adjust the low end needle valve to where it reached maximum RPM's. Seemed to work, had good transition from idle to full power. Have been using this method since the early 90's. I'm sure it does the same thing as previously described, but if having trouble setting your low end, try this method ?

Cary

Tcat1000

My Feedback: (34)

Hi.............I am currently running five of the 55AX engines on five different planes & have never had a flameout as described in above posts. Hmmmmm...........

On all but one of the planes with this engine, I have two full seasons on them with a lot of flights. My planes are H9 Twist 40, Ultra Stick 40, Drastick 40, Escapade 40, & a second Twist 40.

I do a lot of touch & go's when the field is not crowded & they just transition great. Here is my setup & may be the reason of my success................

15% Wildcat blend 18% oil
APC 12 X 4
OS A3 or type F plug
Macs black muffler # 6590 on four of them & stock OS muffler on one of them

Maybe my higher RPM's are helping........or the Macs muffler.........I wonder

Anyway that's my story & I'm sticking to it...........I went through 14 gallons of fuel past season so I fly a lot...........

Tcat

mustangman177

TCat: Is this the muffler you're referring to ?

http://www3.towerhobbies.com/cgi-bin...&I=LXXYM3&P=SM

Did you notice any rpm using this muffler ? What kind of rpms are you getting with the 12 x 4 APC pro ? I've read that the 55 AX is not really known for its high RPMS rather more of a higher torque engine ? Take that for what ever it means.

Thanks

Cary

Cyberwolf

My Feedback: (4)

I don't know mine with a 12x4 has almost scary RPM's, just from the sound I know its beating the 46 FX and AX with the same prop. It's always had way more grunt than I have needed for the app I used them in, so I never bothered to do a tack reading with that prop. But I will, as soon as the weather permits and I think the results may supprise a few.
Oh I normally use the 12x25x3.75 APC and that works well for me.

Ernie Misner

Interesting. Of course it is actually "doable" because the LSN is slightly angled back from the carb. I would definitely check for stalling when you abrubtliy open the throttle from idle before flying though. Faulters, and it is a hair too lean......

Ernie Misner

albsurfer

I believe Tcat1000 is using the 12x4 & 12.25x3.75 APC for mainly 3D & fun-fly type aerobatics. An 11x8 APC gives this motor great RPMs for fast flight on the .40-.46 sized planes. 4 of my flying buds are using that setup on Escapade 40, Extra 300 .40, Edge 540 .46, and a .46 Hurricane. A couple of my flying buds are using 12x6 APC for all around flight because their 55AX's will run them. My new 55AX will turn a 12x8 just fine without overheating & I use either Byron's, Wildcat, or Power Master 15% Nitro / 18% oil. The low end on my new motor is still sensitive to weather changes of 4 degs or more. the high end doesn't usually require more than a small tweek now & then with the weather changes.

Ernie Misner

Yes, why is that the low end on the 55's are sensitive to weather changes like that? Most aren't that sensitive.

Ernie

seaeagle2323

Hi guys just ran my plane again did some more leaning on the low speed, for the first 1-2mins of the first start its a bit rich ( might be because i use a lot of after run oil lol) after that its great i can go 0-100 slow or very fast up down up down no problems no lag at att, i just adjusted the high speed to peak rpm and turn it out another 45 degress or so to make it rich, i run at about 90C on the cylinder i use a hitec sensor (so probably not %100 correct might be slightly warmer) i am flying tomorrow ill use a rpm sensor to read my rpm of me 11X7 prop

Tcat1000

My Feedback: (34)

Yup Mustangman, That's the Macs muffler that I am using. I also don't know the RPM's that I am turning, but again I can say again my setup just works.

Keep in mind that my 12/4 APC prop is not loading the engine as much when I nail it after say a touch & go that some of you might be getting using a higher pitch prop so maybe that contributes to my no flameouts!

I also am flying a Twist 40 with a Evo 60 on the nose with that same Mac's pipe & also a APC 12/4 with a OS # 6 plug. No hate mail either because of my prop setup as again it works for me & also works great.

Yes, I am probably turning a ton of RPM's but I haven't disingerated any engine yet in my 32 years of flying & if I do, I won't be whining to Hobby services or Horizon.......I will just put another one up front.

I have seen a lot of fellow flyers at our field in my eyes that are over propping their birds & having issues.

I am not saying this is the answer to anyone's issues, but if it works for me, I'm happy.................Wind em up boys a bit more & I bet you will have better luck with your problems.

Yes, I understand different styles of flying requires a different size prop, but when it comes to selecting a prop I rip that page of the engine manual right out of the book & use it to start a fire!

Tcat1000

mustangman177

TCAT:


Put 5-6 flights on my 55 AX yesterday without any problems. Cooler temps-in the 40's. Would this help engine performance. Denser air and cooler air temp. might make for more favorable engine running conditions ?

I WILL try the 12 x 4 APC prop selection you described. I have several on my prop wall. The mufflers have been ordered from tower. and will run at a higher rpm level.

Cary

Ernie Misner

Yes, cooler temps means denser air, means more oxygen getting into the engine, means slightly richer tuning, means more overall power.

Was it the Mac's mufflers you ordered? Be sure to get the one just for the 55. Be sure and try a 13x4 (not wide) APC as well. Keep us posted.

Ernie

jaka

Hi!
For sport airplanes that not are intended to hover the APC 12x4 is much to small! a 11x7, 11x8, 12x6, 12,5x6 or 13x4 are more suitable!

mustangman177

Ernie:This is the Mac's Muffler that I ordered.

http://www3.towerhobbies.com/cgi-bin...&I=LXXYM3&P=SM

Will let you know how it works. Do you think a 12 x 4 APC is too small for this application ?

JAKA: Will try the props you suggested. Don't want to over rev the engine, but this particular engine has "Issues" and may need the smaller prop to stay running.


Cary

NM2K

My Feedback: (14)

"Issues" are precisely what the warranty is for, if still in force. They can't fix a problem if they don't know about it.


Ed Cregger

Ernie Misner

Yes Mustangman! That's THE pipe for the 55! You'll be amazed what a difference between that and the stock muffler, and yes, a 12x4 is a bit small, will wind up like crazy though with that pipe and everyone will run when you fire it up! It will hook up and get into it's power band much nicer with the 13x4 for most applications like fun fly and 3D. Actually I like to fly my sport planes in close and personal and use the 13x4 for them too. The vertical performance will blow your socks off. Can you say straight up, fast, fast, fast? Try shooting straight up then chop the throttle quickly to idle and throw the sticks in opposite corners and watch her come to a stop up there while tumbling..... fun.

There's another version of that pipe that you can see at Outlaw Hobbies, made more for profile planes. More $ but works slick on a profile job, engine on it's side, and right thrust added which puts the standard pipe in too close to the fuse.

Keep us posted, thanks,

Ernie Misner

mustangman177

Received my Mac's black header pipes for the OS 55 AX and they work great. Instantaneous throttle response and top end RPM's are great. Using a APC 12 x 5 prop for now. Will try the 12 x 4 later Thanks for the info. on these.


http://www.rcuniverse.com/gallery/ga...mberID%3D16901

http://www.rcuniverse.com/gallery/ga...mberID%3D16901



Cary

NM2K

My Feedback: (14)

Just for the record, your "black header pipes" are actually uniquely/aesthetically pleasing and constructed plain old restrictive mufflers. They offer no performance boost over open stack performance. Let's try to keep the terminology straight so as not to confuse one another.

No offense, nor smarty-pants attitude intended, my friends.


Ed Cregger, NM2K

Ernie Misner

Hi Ed, I always thought the mac's black mufflers just saved a little weight and were one piece which is nice...... until I tried the extra volume one made for the 50, 55, and 60NX. They make a huge boost in performance over the stock muffler, similar to a mousse can setup. I guess you are comparing to old school, open stack with no muffler or pipe at all though huh?

Thanks,

Ernie

albsurfer

I agree with Ernie. I had one on a ST-51 and it definitely made a difference over the stock muffler.

NM2K

My Feedback: (14)

I did wonder about the mousse can effect. Thanks for bringing it up again and for not being offended by my comments.

Sometimes a bit of back pressure can be a good thing.


Ed Cregger

davehansen

got a new os55. broke it in per manual instructions. after 5 flights the engine wont advance to full throttle from idle. all the experts at the field have tried to adjust with no luck. running 10% cool power. no fuel line leaks. advice?

1QwkSport2.5r

It’s probably too lean. Depending on where in the throttle range it dies will determine which side is lean. Most likely lean on the high and low sides.

N1EDM

My Feedback: (2)

I will toss in a couple of thoughts...

How long has it been since you broke in the engine? If it's been a while, you could have a tank full of half-evaporated fuel. Were the fuel lines left unplugged?? Fuel lines connected to the engine are not considered to be 'plugged'.

Even with the addition of some fresh fuel, any old, left-over half-evaporated fuel in the tank won't work as well.

How is the plug? It it a no-name plug or a OS #8 or A5 plug?

What were the break-in runs like? Were they the 'slobbering rich' kind that we used on the old ringed engines (and the ruination of ABC engines) or was it per the manual?

Just a few questions to pose here as I have made a lot of these mistakes myself over the years... I learned a lot of lessons the hard way.

Just my $.02,

Bob

1QwkSport2.5r

Often the break-in outlined in OS manuals is incorrect. Proper ringless tapered bore engines should get 30-45 minutes on the test stand, and generally, with a 1” shorter prop than the intended flight prop. Break-in fuel should be a bit more oily than the normal running fuel just to help with keeping tight engines well lubricated; especially in an OS engine with a somewhat fragile plated liner. But!! OS engines aren’t that tight and usually will be broken in inside the box by the time they arrive on the retailers shelf. Lean engines quit. If an “expert” can’t get an OS to run right, then they aren’t an expert. OS has literally dumbed the model engine down far that anybody can run one.

N1EDM

My Feedback: (2)

I respectfully disagree. I have two OS-55AX's and they both run like a top, broken in to the manufacturer's specifications.

Rather than debate this needlessly on this thread, let me offer this up. In the November 2001 issue of MAN, engine man Dave Gierke wrote the following article. Anyone who has been around engines for a decade or two will recognize Dave's name.

In this article, he doesn't use the Do-It-Because-I-Said-So approach. Instead, he digs right down into the engine metallurgy to give a foundation for his reasoning.

IMHO, this is the best article I have ever seen on breaking in an engine.

Just my $.02,

Bob