was wondering if anyone had a problem with the os 50 my low speed screw keeps breaking off in the crab during flight it has happed twice ... does anyone know why ??????? i don't have a clue

How old is this engine? Sounds like you have a ton of vibration? I would check the bearings in the engine and the heli for any vibs! I have amny gallons through my OS50 and never had a problem like that.

I fly a Os 50 heli motor in my Fazer FF and my Ergo, I have never had issues like your. Check for:

A lateral vibration , an unbalanced rotor head possibly having one blade heavier than the other.

vertical vibration, blades out of track will cause this sort of bouncing motion.

Low frequency vibes, rotor involved here if slop is evident somewhere.
Other than this this could be a hard one, if you find nothing wrong vibe wise. I would call Great Planes, I believe they could help you with a motor issue such as this.

I haven't had the screw break off, but I am having trouble getting a good linear mixture. According to the instructions, you should tune the low speed screw according to how the engine throttles up through midrange. Mine goes very rich just above Idle and just below a hover speed. But Idle is Lean!?

I have the screw turned all the way clockwise that it will go and the idle is uncomfortably lean but when I throttle up to hover it goes slobbering rich and sometimes quits. Occasionally I can nurse it and the blade speed will pick up and I can hover comfortably and even FFF and loops. Then, occasionally it will go into that "fat" condition (usually after throttling back and back up after a loop) and I am in a panic descent with low rotor speed and no power cause it sounds very rich.

I am about to flatten this engine on the nearest railroad tracks and put a TT 50 in it.

I have been flying glow engines for over 40 years but this one has me baffled.

Any suggestions?

I fought with this problem when I tried some fuel that the engine DID NOT LIKE AT ALL!! I switched back to CP and havn't had a problem since. I love the OS 50 engine but the type of fuel makes a HUGE difference. I have a fuel pump on mine now and now the mixture stays constant the whole tank, very nice! My OS 50 HATES Power Master and Magnum fuel.


I was out flying my heli the other day (in between crashes) when I started having trouble starting it, no matter how rich I ran the needles it just kept running lean at low end! Mid end was fine but top end was a little low on power. I had a LOT of trouble starting, also. I thought my plug was bad but when I was looking at the engine to check the glow plug extension I noticed the line that runs from the crank case to the fuel pump was broken!!! I couldn't belive my engine was running with a HOLE in the CRANK CASE!! I was shocked!!! I really like this engine a lot!

TEAMERICA
What kind of fuel are you using?
What kind of plug?

Unless you have a really old one the OS 50SX-H does not have a low end needle, it has one of those strange limiters that only move about 260 degrees. Another thing with my OS 50 is that the pinch test does not work with the idle. I set my engine to idle rough then richen it a bit so that it stops popping all together and then hover it. If I land and it pops I richen it up, if my idle is bad I lean it up. The highend I just play with till my engine stays cool after some high power pull outs. I wish my airplane engines were this sure to set up, I have been having trouble lately with my plane engines because I've let them set so long, I lost the nack!

Well, I am running Power Master 15% right now. I have been running McCoy MC9 Plugs also. I didn't have this problem while I was running some 5 year old Nelson 30% (I had to tell the age cause I don't even know if they are still in business). The Nelson was stored in a cool dark place for those 5 years while I played with fixed wings.

I only got this PM 15 because HP had a $9.95 sale over a holiday. I usually mix my own but can't mix it for that cheap. I just mixed up some of my 25/20 today and will try it tomorrow. Maybe that could be the answer. I plan to also try the OS #8 plug but only want to change one thing at a time so I know what resulted in what.

Yes, My OS 50 has that little "half turn" mixture screw. They don't like to call it an Idle screw and rightfully so, since it adjusts the midrange. It is a relatively new engine with less than 8 gallons. If I try to lean the top end to solve that fat midrange, I cook the engine in FFF.

I agree with your practice of tuning the High End according to your last flight. Too many people like to "tweak" before EVERY flight and that is just asking for trouble.

Dan

it's a new engine ... i have less than a case of fuel threw it ...
no noticeable vibration .. until the screw breaks and the engine starts missing

How does the screw break off, Elvis? That would be helpful to know.


TEAMERICA, 15% Power master with 23% oil heli fuel was HORRABLE in my 50. It stank, smoked like a smoke bomb, and the mid end was as rich as eggnog! I had to nurse it like you did, if you can try some CP 15% in it, or maybe your home brew will work. I don't know about the glow plug but I spent hours messing with that power master. I know what you mean; I also cooked my high end to get the mid range even close.

I also had problems with Magnum 15%, I usually run CP 15% but will try some CP 30% soon, and I can't wait! The CY muscle pipe I put on really helped the idle. Very low and reliable idle now. I know this sounds strange but the CY muscle pipe makes the engine easier to tune because you can hear the change better.

thats what i want to know ..i don't know how it breaks . but it does

Sorry, I meant to say "Where does it break at." I said how does it break as in what does the broken part actually look like?