evanspa

I have a fairly new OS 55ax. The darn thing Quits after ~2min of flight. Starts easily, Transitions great, Full throttle no Prob. All on the ground. Break-in completed properly. I have changed the tank, lines, plug and fuel, Same story. Tank height checked all is good. Cleaned carb, seals are good. Engine will run all day on the ground. Props 11x7, 12x6 and 13x4. There is no Cowl. Engine is on a GP Escapade running 15% Master
No Love. Top end seems to have a large "Flat" spot when tuning.

The AX is no FX thats for sure.

My Questions:
For anyone experiencing the same prob,
How did you cure your Deadstick Problem?
Which Muffler original square or new round.
Anyone change thier carb to something other than stock?

This motor is starting frustrate me.....alot! There just seems to be too many people with the same issue.
The last thread of people trying to find an anwer got closed(?) I was told "There is no Deadstick Problem with the 55". I see alot of posts regarding the 55ax with the exact same issue. Alot!

MinnFlyer

My Feedback: (4)

This may sound strange, but check that all of the head bolts are there and tight.

If that's ok, the next thing I would check is the low end - again, that might sound strange, but I've had engines that did the same thing until the low end was adjusted. Although my 55AX has never given me a lick of problems.

evanspa

Thanks
Yep, checked all the Bolts and seals. Low end and HSN needle have been adjusted to just about every possible position. I have tried every suggestion on the web. Except bearings. Fiqured after 20 years I should be able to tune a motor, guess not. LOL
The only cure Ive found, swap for a 46.
What Muffler do you have?

MinnFlyer

My Feedback: (4)

The square one

evanspa

I have a Square I can try. Thanks I'll post back this weekend with results.

Jetdesign

My Feedback: (8)

Sounds to me like the top end is lean. That would explain your 'flat spot' on the ground and cutting out in the air. I guess it could also be the low end, but either way I think something is lean.

I've had a few AX engines and they all are amazing, including the .55 (of which I've owned 2).

Contrary to popular belief, true breaking-in of the engine takes a few gallons of fuel. This can be seen as you will start to develop more power and better fuel efficiency. Probably between 4-6 gallons of fuel. This has been the case in my experience with all 5 AX engines I've broken in.

My suggestion is to enrich your fuel mixture. If you don't have perfect transition, give it some time.

evanspa

I did try a rich setting on top end and low end.
The flat spot I was refering to is when adjusting the HSN, When I set for peak, then back off, I need to turn the needle out many clicks before the RPMs back off. That is the reason I was asking about the Muffler, I was thinking might be a Back-Pressusure issue.

gaRCfield,
Which muffler do you run?

Jetdesign

My Feedback: (8)

Stock muffler that came with it. I think it's square.

Sounds to me, from your recent post, that you have a fuel delivery problem. Either pressure to the tank is too low, the tank is too far from the engine, or there is a small leak and you're getting excess air.

Insufficient flow/excess air would show itself as little effect in leaning the engine when tuning - struggling to find a peak, followed by a drop off in RPM and difficulty making the engine run slightly rich.

Villa

Hi evanspa
So you have been at it for 20 years. I have been at it for over 30 years. I had problems similar to yours on my 46AX. I have solved the problem and all is OK now. What I did was follow the 46AX manual very carefully. I was doing something wrong, or perhaps the wording in the manuals have been changed slightly from the 46FX engines. I was adjusting the Low Speed Needle valve wrong. In years gone by I would compare the manuals word for word till I found something. At my age now I don't care how it happened. If I follow the manual very carefully I get great results. Try it an let me know. Especially if you (or others) find something different in the manuals

evanspa

I was adjusting the Low Speed Needle valve wrong.
Can you elaborate?

ChuckW

Both of mine have been flawless right from the first start but I did notice a couple things when adjusting the carb. The high speed needle seems to have a fairly broad range where RPM doesn't seem to change much. With most other engines you find peak RPM and it will change within a couple clicks either direction. With my .55's and my .75 it seems like you can turn the high speed needle quite a bit either way with no detectable change. This makes it very easy to get too lean or too rich. I also found the low speed to be way too rich out of the box and had to lean it quite a bit on both engines.

I'd also look at your fuel. I had a 4-stroke once that I just couldn't seem to get right. Used fuel from a new jug one day and all the problems went away. I must have left the other one open too long on a damp day or something.

Piperkronie

I've had similar problems with an evolution 46. Turns out the low speed setting was too rich.

On the 55ax I have, after I broke it in, a couple of the guys at the club adjusted it by leaning out the low end a bit, and I haven't had any trouble with it. That's when I decided to re-visit the evolution - it's worked great ever since.

On the evolution, I needed to re-set the low speed needle (i.e., open the low speed needle to make sure you don't damage it if you've messed with it like I did , close/set the throttle/carb to 'just open' (around 1mm), close the low speed needle and then set it by openning it - on the evolution, it was 1 1/5 turns based on searches here. Once it's running and warmed up, I just tweaked it.


Here's a post that I found helpful.

http://www.rcuniverse.com/forum/m_69.../tm.htm#694681

evanspa

The Carb on the 55AX is a lot different than the 46AX or FX the spray bar is different.

Villa

Hi evanspa
As best I can remember, the manual instructions require the carburetor barrel valve to be in the fully closed position. From that position the LSN valve is turned in till it stops and then opened a certain number of turns. I believe I did not have the barrel fully closed. Be aware that the position of the needle valve can prevent the carburetor barrel valve from closing. Let me know how you do.

evanspa

Thanks,
Right now I'm only about 1/8 in from break in.

jerrysu29

I just broke in three of the 55AX's after break in checked the transition from low to high idle didn't have to change any of the low needle settings. The high needle when peaked will change the RPM @ 80 rpm each click when turned out to richen I checked all 3 with a tach while doing this. One other thing I do after brake in is to bring the engine down to an idle let it idle for three minutes at about 2700 rpm and see if the idle stays the same after three minutes if it increases the low end is lean if it decreases the low end is rich. I did not have to change the low needle on any of these engines. After 3 minutes of idle I advanced the throttle and all three of these engines responded with no hesitation or sputtering. You have a 2 year waranty with that engine I would box it up and send it in.
For what it's worth we have over 50 members in our club and most of them bring there new engines to me for brake in They Think of me as the local engine gooroo LOL!
jerrysu29 Call Sign Wild Man