Os 55ax
 

tried everything to get this motor to run smooth good tank position cleaned out all fuel lines could it be that the motor is inverted ? just wont idle in the air dead sticking it every time I throttle off !!! Could someone please give me any suggestions on what the problem could be?

[QUOTE=izzy-israel- Could someone please give me any suggestions on what the problem could be?[/QUOTE]


Failure to maintain the same fuel tank to spraybar (jet) relationship in the inverted position as it would be in the upright position.

That's the bottom line your tank is too high! This happens often when the fellows invert and do lower that fuel tank to match how much the spray bar was lowered.

Lower that tank, get out the chainsaw to do so if necessary or just mount the engine sideways.

John

tank is in good position its a seagull fun fly motor has to be inverted .

flying a fun fly made by seagull the motor for this plane is to be inverted.

Don't be so sure of that. Not uncommon at all for any number of these ARF producers to setup incorrect fuel tank arraingements in some of these inverted ships. Not uncommon at all. I see some product coming from a variety of producers with all sorts of inconsistancys such as wildly incorrect CG recommendations and in the case of some inverted ships with totally terrible tank setups.

You want the problems to go away either lower the tank/spray bar relationshop to the manufacturers recommendation (OS) and you will find that in your engine manual or rotate and mount the engine sideways.

John

Idle screw is possibly out of adjustment.

How are the deadsticks happening? Is it at full throttle, when transitioning, during a maneuver, at idle, or random? How does the engine behave when it deadsticks? Does it gurgle and surge, get low on power, or just quit suddenly? Have you worked it on the test stand and checked the mix with the nose up? Have you checked the tank lines for leaks (it can happen to new ones)? Have you checked all of the bolts and locktited them in place? Carb and needle valve o rings ok?

random when at full noise throw off she dies haf throttle throw off she dies! runs fine in the air!

What does throw off mean?

throw back on the throttle

back off on the throttle

So it's dying when you back off the throttle then and it happens at both midrange and full throttle? If that's the case, I'd suspect an air leak either at your high speed needle, carb o-ring, or fuel line near the carb. The reason I say that is that when you cut the throttle the intake vacuum is at its highest, which will make any air leak at its worst. Of course, if your low speed needle is too lean that could be the issue as well.

thanx Jester I will check out the lines, putting it on a bench today sick trying to work out what's up with the bloody thing, but thanx for the pointers ;)

I've had trouble with engines cutting out at the top of a hammerhead on one plane. It has been when I had a perfect idle mix and a fairly low idle setting, which made it go lean when I chopped the throttle at that zero gravity moment. A click or two richer and a little bit more idle speed fixed it.

put a four stroke glow plug in seems of to done the job !

You said you were putting it on the bench, so did using the four stroke plug help when the engine was upright on the stand or back in the airplane in flight?

John

No John after I put it back in the plane, it still was playing up again soon as put back in plane, had it running great on the test bench good throttle response good rpm no good response all round. I was told that cause the motor is inverted I could be flooding the glow, os 4 stoke glow plug in and seems that it has done the job. I also had probs with the plane leaning out after ten minutes in the flight found out it was the tank vibrating causing the fuel to bubble causing are bubbles in fuel put some foam around the tank .

I have a 120 AX that loves and "F" plug. They are made for 4-Strokes but do wonders for the AX engines.

is the 120 inverted ?

No it is mounted on its side. But I did experience a couple of random flameouts with a well tuned engine. The F plug put a stop to that.

What size prop are you using on the 55?

At first I used a APC 12 1/4 - 3 3/4 ran ok probably under propped a bit was making a bit of noise in the air, then went to a master air screw 13-4 as I just wanted the plane for 3D flying and I really just want to do a lot of hovering or hanging it off the prop so thought that 13-4 would give me plenty of pull being big diameter small pitch should hold the plane nice in a hover anyway at this time had a accident with my thumb and a prop so couldn't really master the rudder with my thumb bandaged so 3D flying was on hold for a few week's, 13-4 master air screw was barking at full noise as could only fly in circles with the thumb the way it was had to pull back to half throttle as the boy's said It was hard hearing each other lol,, so then I went to a 12-5.5 still made noise but not as bad as the 13-4 and also made the plain fly a lot betteras it was a windt day. Explained that the 13 -4 was for hovering or hanging it off the prop it wasn't really for normal flying. Still don't know how the 13-4 will go hovering the FunFly yet to try as of my injury .
I am up for any suggestions on prop sizes for the 55AX