nappy99

I have OS 120 AX in FuntanaX100, on 20% Wildcat, APC 17x4 prop. On the ground the motor runs perfect, I can't get it to stall no matter what I do. Yet in the air, the motor leans out in level flight at slower speeds (below 1/2 power) and sometimes it stalls on spool up. I opened the low needle from 3/4 to 1 turn, and helps, but now I seem to run to rich, constant smoke trail, it will not stall now, but stumbles a bit on spool up. It runs much better, yet for 3D I am not comfortable it will not cut out on me.

So will a Perry Pump help make the motor run constant (air/ground) no matter what attitude the plane is in ? Anyone try a perry pump with the 120 AX ?

Any help would be great.

Thanks

jzinckgra

My Feedback: (11)

I have the same combo and have no problems. I'm running 5% OMega (pink stuff) with xoar 17x6. The tank on that plane, placement wise should not be an issue, so in your case, doubtful it is starving for fuel. the stumbling on spool up is probably your low speed being set too rich. A 1/4 turn was most likely too much. Try leaning out 1/8 turn. The other way to test low speed is to let the plane idle for a minute or so, then go full throttle quickly. Any stumbling on the transition would indicate too rich a setting for the lowspeed. i don't think the perry is necessary on this plane, but just my opinion.

mrbigg

My Feedback: (21)

So will a Perry Pump help make the motor run constant (air/ground) no matter what attitude the plane is in ?


Yes.

McChiken

Hey Nappy99 , Did you ever figure out your problem with the AX ? I have the .75 with the same issue . Ended up quiting after a touch and go and I had no safe place to land and tore my front end off my
Aeroworks Edge 540t . It was sputtering at 1/2 throttle and I gave it full and it died right away at about 50 feet when I was making a turn .

I have a .46 ax and it wasnt so difficult to tune. The .75 seems like you can keep turning the top end screw in and in and the RPM's keep climbing to no end . So I dont know if I got it to lean or not . The motor also puts out a lot of vibration putting bubbles in my tank . When it ran without quiting there was hessitation from low end to top end and that was after turning the idle screw out 1/2 turn . I wasn't getting a steady smoke stream either . It was intermitent . I was running a 14X4w APC on it and used a Hayes 16 oz. tank . How do you know when you are getting too lean on the top end when it does this ?

nappy99

Yes problem fixed, it was the low speed needle. I turned it out 1/4 turn, ran perfect. Tune the high speed first, set to MAX rpm, then back down 200RPM, then set low speed

airraptor

My Feedback: (66)

this is a common problem on all the AX engines above 55. my 120 now will now stay running long in the midrange now matter what i do to the idle setting. a 17x4 seems alittle on the small side. i ran a xoar 17x6 with stock muffler and pulled just fine at 10.5 lbs. it wasnt electrice 3d power but would pull out slowly. with a pipe it spins the APC 16x8 at 9,800 peak and about 9,600 just right

nappy99

The 17 X 4 does seem small by "spec"...but I have tested many props with RPM guage and digital thrust guage, and I found a 17 x 4 (w) spools up fast and gives tonnes of bottom end. On a 10.5lb plane, I set my 17 x 4 to 9600 RPM (nice and rich)....and it pulls out of a hover faster than any electric ! Within 5 seconds it is out of sight. If you do 3D, try an APC 17 X 4 (W)...you'll be amazed at the vertical pulling power.

In level flight you stay below 1/2 power (will over rev), but in vertical climb, it pulls amazing. For $20 its worth a try

Flyer95

My Feedback: (1)

Use an OS-F glowplug in your twostroke engines and set the needles slightly rich and I am pretty sure your problems will be gone.

Stuntpilot51

I'm running a Perry pump on my 120 AX and it works fine.
If your using a pitt's muffler you will eventually need to put one on due to the lack of pressure from the pitt's causing a leaning condition half way thru the tank. Or if you have the tank mounted on the CG and your fuel lines are long.

McChiken

I have a .75 ax and have got some good info to tune it properly . I do have a Slimline Pitts for it and was going to use it when I fix the frontend of my Edge and redo the motor position . I want reliability and was looking into the perry pump . I guess you have to drill a hole into the crankcase to mount a pressure line ???? That sounds like you have to tear the motor apart to insure no shavings will be inside after
drill and tapping . Or is the backplate of the motor what the fitting hooks up to , this would be easier ??? What is the method you used and the style pump ? Pics if you have them please .

I am a machinist so I have the capability but the Perry website realy blows and doesn't give much info . I also am hesitant to void my warranty and drill into a brand new motor . I was thinking of moving the tank back to so I might need this . I also looked at the Cline website but it looks like there closing shop due to heath issues .

Stuntpilot51

McChilken,
You just drill the backplate in the center and tap for the 6-32 fitting they supply. The 160 FX has a entrance for the fitting on the top left backplate screw that you can drill and replace the screw, not sure about the 75AX. Just remove the backplate and drill it, make sure you file off any protrusion on the backside. This is about a 5 minute job.
The other thing is use the supplied tubing and don't replace with fuel tubing, that will blow off during the pressure cycle, (not good)
I'll get some pics of my installation.

If your worried about warranty just buy a seperate backplate to install if you have to send it in.

A couple of key points, make sure the vent hole is pointing down and the pump is level with the carb inlet. Don't even mess with the adjustment on the pump as it does'nt do much. It's all in the LS needle setting to get these to run correctly, and to smooth out the midrange.

Don't forget no muffler pressure, just route the line to exit the cowl, with the pump you need a tank vent.

These pics show with a fueling valve so don't get confused on the plumbing. If you have a fueling valve it has to go in after the valve. The second line you see going by the pump is the vent going below to exit the cowl.

Can I ask what your tuning instructions are? There's only one way to tune these or you will be pulling your hair out.


This is the one you want,

http://www3.towerhobbies.com/cgi-bin...?&I=LXDG59&P=0

Stuntpilot51

Here's the foolproof tuning method for the perry pump, if you try to tune with the adjustment screw on the pump, you will lose all your hair, and throw the pump onto the ground and stomp it to death, save yourself the heartache.

Open up the muffler if you've had it blocked off, peak the high end, don't back off rich. Go to idle, if engine idles well for 15 or 20 seconds, lean the low speed 1/4 turn, Go back to the top and re-peak, go back to idle, same routine, if it idles for 15-20 seconds, lean another 1/4 turn, continue this process until engine will not sustain a idle, it should speed up and die within 20 seconds. Now richen the low speed 1/16th turn at a time until engine will again sustain a idle,after each adjustment on the low speed repeak the top end, as soon as the engine will sustain a idle leave the low speed alone. Each flying day just repeak the top end and back off 150 rpm for flying.
You have to go lean to the point of no idle then come back up to get it right. Transition from idle to midrange up to full should be crisp without sputtering. If you run the high speed to rich you will have the same problem with sputtering. My O.S. 160 preforms flawlessly with this setup, I had to lean the low speed 1-1/4 turns to get it to run properly, just make sure you peak the high end and only back off 150 rpm, be sure to use a tach. On my 1.08 it took about 7/8 of a turn on the low speed to get it right.

McChiken

As far as the line hook ups go . The muffler pressure line is plugged . The vent line from the tank is open and hanging or facing down.
Is this correct?

As for the tuning , What does open up the muffler mean ? When you taik about 1 1/4 turns out and 7/8 turns out this is out from a closed position , correct ?

To answer question on how I was told to tune without perry pump......

I was told to get top end set first and then to set low end to a point where engine dies when I transition from low to high throttle . Then
start richning the low end 1/8 turn at a time till I get a smooth transition without hesitation . Pretty close to what your method is with a
perry .

I do have one issue with setting the top end . It seems like I can keep going leaner and leaner to no end and the rpm's keep climbing and climbing . Im having a hard time figuring where im actually topped out on this motor . Is this normal?

Also , Why do these AX's put out a raspy vibrating noise at certain rpm's . I heard one on you tube that did the same noise like what
bad bearings would sound like . My .46AX does the same thing .

Thanks for all this good info.


- The Chiken Will Soon Fly -

Stuntpilot51

I just turned the muffler pressure line into the vent line and routed it to a brass tube out the bottom of the cowl. you should'nt have a vent to begin with on the 75AX. If you look on the pump there is a little vent hole on the black part of the pump that needs to face down when installed, the instructions with the pump spell this out, you'll see when you get one.

Most people have plugged one outlet of the muffler to create more pressure before they tried the pump. This is usually the first remedy for losing pressure with a pitt's.

Sounds like your tuning method is real close, the idea is to just get the LS barely rich enough to idle as the pump is forcing so much fuel thru the carb. The LS needle controls over 75% of the throttle curve, it is more important than the HS needle for a nice running engine.

Run the needle in until the engine starts to slow down to record your top RPM, immediately richen when you hit that point. with a 17X4 your going to get up there pretty high. When you done turn the needle in to figure out how many turns out you are from closed, just for reference. Being from California, you should'nt have much change on the needle thru the seasons as we do out here in the boonies.

The LS needle setting was the number of turns in from the normal operating position without the pump, not from closed. Your's will vary due to fuel, temperature,altitude and prop.

My HS needle will be anywhere from 7/8th to 1-1/4 turn open with the pump, so much fuel is being sent in the needle needs to be closed that much. I also just centered the adjustment screw on the pump. When your done you should have a nice strong smoke trail from the engine during flight, much more than normal without the pump.

The AX line has had some people complaining about bearing noise which might be your raspy noise you talk about, I had the same noise on mine but after about 10 tanks with the pump it went away. I checked the bearings and they looked fine. There's been alot of discussion over in the glow engine section about this, no one really has an answer, I would'nt worry about it, just check the bearings when you have the back plate off and if there rusted give RC bearings a call for a new set. $10 You might need a set in the salt laden air out there.

McChiken

I really appreciate all the help Stuntpilot . I'll be getting my perry on monday . I hope to fix my plane tommorow from the low stalled deadstick . I'll do this while I watch my Raiders loose to Denver .

Just outa curiousity what size tank do you run with your 120 ? When my .75 ran for two five minute flights I still had 2/3's of a tank left with a 16oz'er . I was thinkin of getting rid of some weight when full and put a 12oz. in.

Do you like that rubber mounted motor mount ? Does it keep the tank from getting bubbles ? I thought of using one of these for my Saito but they look heavy . I almost wish I would have got a Saito 100 instead of this .75 but this is giving me some good experience . In repairs and tuning . Although the Saito did take me 6 months to learn to tune .[X(]

Jetdesign

My Feedback: (8)

I have a perry pump on a 120AX and it works great. The 120AX has a spot right on the center of the back plate that looks like it was made for mounting the pressure tap. Also, I had a problem (not related) with my AX; I sent it in with the back plate drilled out and they still honored the warranty. So, just pull off the back plate (4 screws) and mount the tap right in the center of the back plate. The pressure tap won't go all the way through the back plate, so no chance of interfering with the internal workings of the engine.

With the pump, you tune the engine so it's just off peak rpm, like 75-100 rpm just to make sure it's not lean. The plane will not lean out in the air, or at any attitude. It's really a sweet contraption.

Cover your muffler tap so you don't leak exhaust stuff everywhere, and only use the pressure from the back plate to the pump. A line goes from the tank to the pump, from the pump to the carb, and a vent is needed on the tank for ambient air to enter.

Last thing: you want your needles set from before using the pump, then tune the pump to the engine. You should have your low and high mixes set with the needles, and adjust the pump for smooth transition, and obviously slightly tweaking the needles if necessary.

Stuntpilot51

I have a 16oz in my 120AX gives me around 12 minutes. The 12oz should be fine for the 75, should give you around 15-18 minutes. I have a 16 oz on a 61 size trainer and have gone 25 minutes.

The Iso mount works good, although they are a bit heavy, reduces vibration quite alot. You still want to pad your tank on all sides.

The mount is more for vibration on all the electrical equipment and the airframe than the tank.

gaRCfield,
I do remember the raised area in the center of the backplate on the 120, made just for a tap. I wonder if the 75 has the same.

McChiken

Yeh , the .75 has a raised area in the center big enough to drill and tap . My .46 does to but it is not big enough to drill and tap . I think it is part of the design on the casing to add strength .

I will be padding all sides of my tank now . The original design of the plane had the tank fitting through a plywood structure in the fuselage with no room for foam except in front of the tank and behind it . Since im rebuilding the whole bottom front end of the plane I will be able to make room for foam .

The pic with the big round nob in the center is the .75 the other is the .46 . I also made about 8 sets of these motor mounts outa T6061 aluminum and am going to try and implement some rubber in them like those ISO mounts you have .

Stuntpilot51

Engine mounts look good, it sure is nice just to be able to knock out a pair out at work.

Perfect spot for the pressure tap on the 75.

Let us know how it works out.

McChiken

Hey Stuntpilot51 , I'm almost ready to test my perry out. Took a while and lots of motivation to fix my Edge but its done . I went anal and made a hatch to get to the motor mount screws and made a removable fuel tank craddle with foam padding .

I have a Question on the fuel tank . The instructions on the Perry say to use really flexible line so on a long nose down it won't run the pump dry . I have never seen a tank big enough or line flexible enough to reach the front of the tank in a nose down . If it did I would think it would kink or wrap around the pressure line . How do you do your tanks internal fuel line ? Does it go almost to the back of the tank or do you shorten it so the clunck is in the center of the tank . Mine is in the rear of the tank now and can hit the top of the tank if inverted . I like doing blenders and spins and don't want to run out of fuel ,but then again I never have been nose down long enough to kill a motor on any other plane .
Maybe i'm using the wrong fuel line in the tank . I use medium size or standard fuel tubing .

kid chuckles

I use an osiclating Perry Pump on a Saito 125 because of where tank is mounted. I had alot of flooding issues with the tank being about half in. above needle valve. Starting was a nightmare and Deadsticks were constant. Now i don't even need a starter. It runs smoother that ever before and have had not one deadstick. I still use muffler pressure to keep tank presurised. Best thing i have done for that motor, and so easy to mount anywhere on firewall will work. Had the pump for a yr. before deciding to try it as i just didn't believe in them (had never used one either) now I just prime it and then Chiken Stick. Sometimes i already have starter out for other planes and start it first time with it. Primes faster that way but don't need to, and then it is just a flip or two and there she goes. Perry had a good idea when he invented this ocisialting (SP) dumaflagy.

kid chuckles

sorry wrong topic for the post I had that dadgum back arrow lol.

McChiken

Maybe one of you can help me out again . I have the perry on my edge with the .75ax and am still having problems . I sent this letter to O.S.(greatplanes support) and figured maybe one of you might have had the same issue .

Support,
I bought a .75ax and have had nothing but problems . I first tried to break in motor like the instructions say . It will not run at any high speed at a rich highspeed setting . I also have the .45ax . It will run rich . I fly around a little after I think it is running fine with a good transition . And it dies . I ended up tearing the whole bottom front end outa my Edge . I fixed it and decided to put a perry pump in it . I also put a new tank in it and wraped the tank and the box the tank fits in with foam . Now it will idle forever on the ground and go right to full throttle with no problem at all . I have gone full throttle and held the nose up and down , let it idle for 2 min. and nose up for a while and down and it works great . I then go to fly it and it works great for 5-7 min. and when I set up for a touch and go it dies when I lower the throttle . What the heck is going on . I have tried new plugs(#8os) and that doesn't help . Why before I put the perry on it won't let me run the throttle up when it is set rich on the top end ? Is something wrong with this motor ? One guy suggested I run a O.S. F-plug in it . Another guy thought the plug was going cold . I have never had these problems before and even got a better brand of fuel(powermaster 15%) . My other motors work fine so I know I'm not completly ignorant on tuning them . I have 2 Saito's , 2 O.S.'s and 1 Evolution . Help please .

If I can get it to quit dying it would be great . The plane flys awesome still , considering what I did to it on the earlier deadstick . Nice KE's and wicked tumbles . I'm really about to give up on OS motors. Just buying Saito's will be my next route .

edit; I failed to mention I still have over 3/4 of a tank left when I land it deadstick

Jetdesign

My Feedback: (8)

I'm sorry you are having troubles with your O.S. First I have to say do not give up on the AX engines; either there is some small thing that is not right, or there is a small possibility something is wrong with the engine, in which case Hobby Services will more than hold up their end of the warranty, and very quickly.

I think the most important thing to do is to get the engine running properly without the fuel pump, pressure line for the Perry pump closed off, and with the tank near the firewall. Return the engine to it's starting settings (high speed needle 3 full turns open, mixture screw flush with the throttle housing). From what I read above the engine has not really had some good running time for break in. It will probably have a slightly boggy transition for a few tanks of fuel. Don't adjust the low end until you've had a good amount of fuel through the engine. When you're satisfied with the top end, you can start working on the mixture screw to adjust the transition. If you don't do this before you hook up the pump, you will never get accurate settings and have a really tough time getting a good transition.

Once your needles are at least really close to the right setting, you can reinstall the pump. The idea is to tune the pump to the engine's settings, not try and tune the needles to the pump. When everything is setup properly, the mixture valve will control the idle, the pump will affect the transition, and the high speed needle will control the top end.

I think the best thing for you to do is post something in the O.S. support forum here on RCU. There are lots of guys, including reps from O.S. who will be more than happy to walk you through a checklist of things to get your engine working right.

I have bought like 4 AX engines in the past year, and am about to buy another one for my Venus 40. They have been so great to me that I can't justify buying something else in a two stroke. I'm sure you will get your problem solved and will end up happy with your 75AX.

Good Luck!

McChiken

Before I put the pump on it the motor died due to the low end being too rich . It hessitated during transition to full throttle and died . Thats when I toasted the front end of the plane . It would never run properly on the top end at a rich break-in setting . After I fixed the plane I bought the pump . I also moved the tank back 3" when the plane was repaired so there is no going back now. I will run forever on the ground it seems like . I can idle however long and hammer the throttle with no hessitation at all . Full throttle at the snap of a finger . My problem is after 5-7 min of flight it dies . That 5-7min of flight it works great . With tumbles , verticlals , etc . I have a .46ax and have no problems with it at all . The 5-7min thing has got me stumpted .