Hello,

i bought a OS46FX for my Dazzler I just finished. I followed exactly the break in instructions in the manual. However after running 3 tanks on the ground i brought it rich in the air. Under rich setting, the throttleresponse was really delayed. well i thought let's keep on going. Now that I have almost 10 flights and the setting are leaner, I still have the trouble of delayed response, especially when I start (I ease in throttle, Although I am at full throttle, the engine only gives 50% . after take off (still full throttle) the engin start sppeding up) Trying to accelerate out of slow flight shows the same.
experienced guys at our club helped me to adjust the valves: the high speed is about 200-300 rpm below max. the mixture was at factory set (1.5 turns out) and at lean set (about 1/8 turn to rich after engines stuttered to speed up)... no difference same trouble.
It also looks like that I do not have these problems to this extend while the plane is NOT moving. When i lean it out to get fairly quick response at start, it'll die in the air.

Any ideas?

THX

Juergen

When you throttle up, does it start sputtering, or bog down?

It comes up a little and then just can not overcome this "hurdle"for a couple seconds til it speeds up. It's more sputtering

Simple - just lean out the low end a bit at a time until your transition is ok. OS sets the low end a bit too rich at times.

Juergen,

How did you break your engine in?
Read the break-in threads in the forum and make sure you followed them. The 46FX is an ABN tapered bore engine.

The correct adjustment of the high speed needle is:
With the plane nose-up, close the needle until maximum RPM is reached (where leaning it further causes a loss of RPM), from there open (richen) by 2-3 clicks. The Dazzler is a fun-fly, with not too much unloading as flight speed increases.

The sole purpose of the high speed fuel needle, is to control the amount of fuel the engine gets, at 80%-100% throttle.

Once this needle is adjusted, it has no effect whatsoever, on the mixture the engine is getting, from 0% to 75% throttle.

Since in both letters you did not bother to mention the idle mixture needle, I conclude that you did not bother to touch it either. Maybe you were not told where it is.

The idle needle is the small screw inside the throttle barrel, on the same side as the throttle arm. In all OS engines I saw, the Idle mixture was adjusted too rich to begin with.
Since despite its name, this needle has control of the mixture at up to 75% throttle, you will not get what you bargained for, until after you have adjusted it correctly.

This needle is very close to the spinning prop, so utmost care must be taken, so as not to get your fingers and your prop into a conflict, over a given volume of air.
It may not be a bad idea to shut the engine down, make the adjustment and restart it to do the check.
Also, when you push the needle with a screwdriver to turn it, it moves enough to shut the engine down, or to affect its running.

Close the idle needle 1/8-1/4 of a turn, with a small screwdriver, gradually open the throttle to full , run the engine at high RPM for a few seconds and close the throttle to about 1mm open.
Allow the engine to idle and listen to it.

If RPM declines gradually, it is still too rich. Repeat the last paragraph until the engine does not sag, then you are in the ballpark. If, on the other hand, RPM increases gradually, you are a bit too lean.

After you finish adjusting, allow the engine to hold the idle for at least 30 seconds, after which you open the throttle rapidly. If the engine goes to full speed immediately, you're done.

If it stutters and spits fuel while speeding up, you're still rich. Close the idle needle a bit more and retry.

If it cuts and dies, or cuts and eventually goes to full speed after a delay, you are too lean, open the idle needle a bit and retry.

Get it right before you try flying again.

Sincerely,

Thanks for your advise. I'll follow the recommendation and let you know how it worked out
THX
Juergen
PS: It was responding perfectly while on the stand. as soon as movment/take off comes into play It delays resond...

I followed your recommendations today. The lean setting forthe mixture was maybe 1/3 revolution out (from closed position while carb was just closed).... run and accelerated great on table. however when on the runway, same issue. engine hesitated to speed up. slowly ran it up to full throttle, kept it for a few seconds and took off with no problems.... in the air slow flight--> accelaeration--> same problem. I spent three hours adjustingthe valve .... when it runs great on the table it doesn, t on the runway. could not find any setting that worked without troble. experienced club members told me that they have never seen something like that.

Juergen

Juergen,

When your model is on the table, is it horizontal, or tilted nose up, like on the runway?
It must be in the runway position.

The fuel line from the tank, to the high-speed needle, to the carburettor; are they as straight and as short as possible, or with kinks and loops (to facilitate refueling)... Make sure they are straight and short.

Break-in; how did you do it (although it should also affect "table manners")?

I cannot think of anything else. Can you take a web cam picture of your engine and piping and add it to the message?

If all else fails, you could ask OS through the forum (down below).

Sincerely,

Do you run nitro in your fuel?

What type of glow plug are you using?

.

Hi!
It sound as if you have a foaming in the tank! But it could be other things to . Hav eyou checked the tank for leaks!

Here is my recommendations and it is for every .46-.50 two-stroke engine on the market.
Use a 11x6 APC prop! Most sport airplanes prefere this size (at sea-level)
Use a OS 8, Enya 3-4 , Rossi 3 or 4 Nova-Rossi 3-4 glowplug,
Use fuel with 5-15% nitro.
Use a 240cc-300cc (8-10oz) fueltank with lots of foampadding around it to hinder vibrations to foam the fuel inside the tank.
The tank should be placed so that the centre is in line with the middle of the carb orrifice when the plane sits on the ground with its stabilizer and wing level with the horizon

If you want the best in fueltanks get a Tettra "bubbleless tank" from Dave Shadel at Performance Specialties in Nevada (he is former worldchamp in F3D pylonracing). This Tettra tank has a silicon bladder inside where the fuel is and pressure from the silencer is comressing this bladder so no air gets in the fuel cell.
This tank could be is glued in the fuselage with silicon glue and it sure will provide better performance than anything you have seen before in.... racing planes that is ....where there is lots of vibration .....But in ordinary sport airplanes an ordinary Du-Bro or Sullivan tank will work just as good

As for throttle drum set up! The idle opening in the carb should always be 1,5-2mm open from fully closed position!
If you use the above set-up then it's just amatter of adjusting the carbs high and low speed needles.....and go flying...remember always to point the nose of the airplane straight up after you have started and adjusted the carb ..slight adjustments are nearly needed before every start, If you want max performance...
Why you held the plane straight up??...it's to check that it can suck fuel without cutting out in the worst possible position (take off position).


Good luck!
Jan K
Sweden

hello Guys,

thanks for yor advise:
-I have used new byron 10/20 fuel (runs great on my saito 100 and LS40)
-fuel tank 8oz
-plugs used OS #8 and Fox with idle bar
-prop used was 10x6 and 11x5
-fuel line to carb were tested with and without inline filter (minimum fuel line length without filter) same result
-breake in as recommended by OS: full throttle and needlevalve adjustment every 10 sec from 4stroke mode to 2 stroke mode
-tank is toataly wrapped in rubber foem. No foaming observed.
-fuelline was bubblefree.
-at idle and nose up... after about 3-6 sec engine dies.

talked to OS service and was told to send engine in for inspection. Will be on a business trip the next two week. As soon as I know whats wrong I let you Know.... any other ideas are more than welcome.

Thanks for your time and help so far I really do appreciate that.

JF

It doesn't look like it from the picture, but I had a muffler pressure problem on a .40 la that had similar but not exact problems as you are having. Set the needle valve like you would to run it, but then take the end of the fuel line and take if off the carb opening (leaving it on the take and remote needle). Now blow through the muffler pressure tap line. Fuel should spill out with minimal pressure, and you should be able to get a small squirt when you blow on the tube hard. You could have a kinked tube(what happened to me), you could have a blocked line to your tank. If you do blow through the pressure line and fuel spills out easily without much hesitation at the begining, then I'm absolutly confused. Let me know and good luck

JF,

Quote:
-----------------------------------------------------------------------------------
-breake in as recommended by OS: full throttle and needlevalve adjustment every 10 sec from 4stroke mode to 2 stroke mode
-----------------------------------------------------------------------------------

WRONG TECHNIQUE.
If OS are actually saying this, they don't know Jack Schitt...

Quote:
-----------------------------------------------------------------------------------
-at idle and nose up... after about 3-6 sec engine dies.
-----------------------------------------------------------------------------------

This would sound like your are too lean, but in flight there is no condition that would resemble this. If you pull up the plane slows down and falls back.
Fuel draw is not as difficult for the engine, as it is when it is held nose up. Transition is not to be checked at this attitude either.
If it was adjusted in "runway stance", it should work right.

Did you check for bubbles between the needle and the carburettor?

Sincerely,

Dar is 100% correct, an ABC/ABN engine should never be run 4 cycling. I remember a while back that this came up in the OS support forum and I believe AMCross said that this was a misprint in the manual from OS.

I hope that they correct the manuals to NOT reccomend 4 cycling.

well, that's still what the manual says! four to two cycle operation during the first run.
Well how to do it right then....(for the next one at least)

Juergen

PSressure test worked well, got fuel out without hesitation...

texfox, that looping fuel line going to the engine is not recommended. It will be blowing and banging around when in flight. Try (just for a test) removing the fuel filter and running a short line straight to the engine.

Ernie

That is a good point which i also tried. I removed the filter with the line to the valve and connected the tank directly to the valve... same result

Juergen

Texfox:

The Dazzler uses a wire rope cable in a plastic outer jacket to control the throttle. If the plastic outer jacket is a little too short, either at the throttle end or the srvo end, the cable will bend before it has a chance to open the throttle fully. This may be one of your problems since the engine checks out ok on the bench.

Good luck.

Pat

Are you guys kidding about the break-in? I have just purchased mounted and broken-in my 2 46fx's the way the manual says and I would be mighty pissed if it now means I will have shorter engine life or problematic engines to run.

Mike,

I am sorry to tell you, but you may have.

If the Nickel lining is still all around, your engines have survived.

Do give them 15-20 minutes of somewhat rich two-cycle running, before checking, to complete the break-in correctly, even though it was incorrectly commenced.

If the plating is in good condition all around the cylinder, you will still have a reasonably long engine life.

As I wrote, OS improved the plating process, to endure and survive the wrong break-in technique...

Sincerely,

Hello!
Come on guys! We all know that the running-in bussines is not that critical!!!
4-cycling an OS won't destroy the engine ...some lean runs though is not good!
OS pistons are not that tightly fit in the cylinder so they will manage a rich setting!

Regards!
Jan K
Sweden
30 years in this wonderful hobby!

you can always put the filter inside the tank between the clunk and the outlet, thats what i did on one of my models

Hello,

OS send the engine back .... should arrive in a few days.... there comment on the phone was: bearing piston and cylinder were replaced on warrenty. Now... where can I find the RIGHT BREAK IN PROCEDURE?

Thanks

Texfox

Regardless of the break in procedure you use (2 minute runs, 1 minute runs, etc..etc..) the most important thing is to get your engine to operating temperature (about 225 degrees F) as quickly as possible. Full throttle operation at a mixture setting just past the 4-2 stroke point will get you there. After this, some people recommend long runs at this setting, some recommend short runs with cooldowns, some recommend short runs with smaller props)