It shakes quite a bit and it makes the whole plane vibrate.

ORIGINAL: Charlie P.

Is the engine mount secure and rigid? All four screws or bolts snugged down tight (those on the mount to firewall and those on the engine flanges to mount)? It won't run properly if it's vibrating that badly. Not only will the tank foam but the spray in the carb barrel can be effected with a really bad case of the shakes.

Is the prop balanced? Including any spinner? Is the hole in the prop the correct one for the engine drive shaft? It should be a TIGHT fit.

ORIGINAL: chris750

Hey guys,

OK i recently purchased a RTF Nexstar, it comes with the OS .46 FXi engine. Apparently it's a great engine and I'm sure it is, but I just can't get it to run properly. The title of this thread says whats wrong with my nexstar's engine, but it may be more accurate to ask what am I doing wrong?

I'm very new at this so it could be something pretty simple that I'm just doing wrong. I know some of you will want to advise me to take it to a club and get some professionals to check it out but I'm not able to do that just yet, reason being that I need to get my radio certified before I can use it at the club, and I can't do that for a couple of weeks because the shop is closed, and I'd like to get the engine running well sooner than that.

The problem is the engine runs really rough and I can't get it to idle properly. By that I mean it just doesnt feel or sound right. It shakes quite a bit and it makes the whole plane vibrate. Also I cant get the plane to sit on the ground without moving forward. If I trim the throttle down enough for the plane to stay still, then the engine just almost stops. It runs somewhat better when the glow plug starter is on however still not perfectly. The RPM slows when I remove the glow starter (some times the engine actually dies but since replacing the glow plug it doesn't really die anymore) and the vibrating is much more significant.

A few more details: I'm using 5% nitro fuel. I've adjusted the needle valve as it says in the manual. It says close fully then open 1 - 1.5 turns. I've done this and then adjusted it slowly from there with the engine running and glow starter removed, 1/4 turn at a time and giving the engine time to catch up. After adjusting this it still won't run properly.

Any ideas on what could be happening? Once again I am inexperienced so please forgive me if I'm doing something completely wrong. Please let me know if you need any further clarification on anything I've said.

Your advice will be much appreciated.

Thanks, Chris.

ORIGINAL: iron eagel

There is also a low end adjustment, this is on the throttle barrle itself with the thottle closed this adj need to be closed also (read manual). I had the same problem with my OS 46 FXI from a Nextstar and this fixed it.
I would be it is too rich at the low end.

ORIGINAL: i live for 3D

If it is a new nexstar, maybe It needs to be broken in more?

Tony

ORIGINAL: chris750


The engine that comes with the RTF version is already broken in at the factory.

ORIGINAL: chris750

The engine that comes with the RTF version is already broken in at the factory.

Based on the popular FX Series engines—famous for superior, long-lasting, low-maintenance power.

Consistently quick and easy to start.

No tuning necessary—comes factory-set for use.

Dual ball bearings offer durability and smooth operation.

Special IsoSmoothâ„¢ engine mount isolates the airframe and on-board radio gear from potentially damaging vibration.

Factory-installed needle valve limiter holds settings within the optimal range, preventing accidental over-adjustment.

The process is
as follows:
1. Install the engine with the propeller
intended for your model. Open the
needle valve to the advised starling
setting and start the engine. If the
engine stops when the glow plug
battery disconnected, open the needle
valve to the point where the engine
does not stop. Run the engine for one
minute with the throttle fully open, but
with the needle valve adjusted for rich,
slow "four-cycle" operation.
2. Now close the needle valve until the
engine speeds up to "two-cycle"
operation and allow it to run for about
10 seconds, then reopen the needlevalve
to bring the engine back to "four
cycle" operation and run it for another
10 seconds. Repeat this procedure
until the fuel tank is empty.
3. Re-start and adjust the needle-valve so
that the engine just breaks into "twocycle"
from "four-cycle" operation, then
make three or four flights, avoiding
successive "nose-up" flights.
4. During subsequent flights, the needle
valve can be gradually closed to give
more power. However, if the engine
shows signs of running too lean, the
next flight should be set rich. After a
total of ten to fifteen flights, the engine
should run continuously, on its
optimum needle-valve setting, without
loss of power as it warms up.
5. After the completion of the running-in
adjust the carburetor at optimum setting
referring to “MIXTURE CONTROL
VALVE ADJUSTMENT� section and
“SUBSEQUENT READJUSTMENT�

ORIGINAL: davo580

bad vibs is mainly due to unbalanced props be careful bad vibs can destroy your plane including rx's. have you put some foam padding around your fuel tank. If the fuel in the tank is foaming you engine will not run right

ORIGINAL: rwright142

Ken,

I will have to check, but I would have bet that my NexStar manual said the engine was broken in at the factory too. The manual you linked to obviously does not so I guess I am wrong, but have to satisfy my own curiosity.

I guess it is always a good idea to break them in anyway huh?

Lesson learned. Thanks for the info.

ORIGINAL: chris750

I've tried adjusting the low end and and now I'm a bit confused.

I tried to lean it out but found that the screw would not turn clockwise which must mean it was pre-set to the leanest setting , could this be possible? I could only turn it counter clockwise which I've done but its still not running how I want. Its either like I described in my first post, running very rough, or when turned the other way the engine keeps flooding and won't start which I'm guess must mean its too rich. I guess what I want is somewhere in between or something?

Maybe I have to keep playing around with it a bit more to get it right, I don't know.

Any suggestions?

ORIGINAL: chris750




I have secured the fuel tank at the back with foam, and a paddle pop stick behind it to keep it secure. It's in there pretty tight.

Well the original prop is back on it. I assume the prop that came with a RTF should be balanced? Or not? If not, is there any way I can check it without a balance stand?

By the way its not just the vibrations, the RPM is not smooth, its speeding up and slowing down slightly, by its self - once again its mainly only after I remove the glow starter.

ORIGINAL: i live for 3D

If the problem is only with the igniter on then you should change your glow plug.

Tony

ORIGINAL: RCKen

Just curious, but are you using fuel from a fresh clean jug?? Or is this old fuel? I ask this because this sounds a lot like you might have moisture in your fuel. If there is somebody else nearby that flies try getting some fuel from them and try again and see if the engine runs better. Or if you have another jug of fuel try that.

Ken