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os 50 sx!!

Old 08-13-2004, 01:06 AM
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Default os 50 sx!!

hi to all,

anyone who is having problems with his os 50 sx?cause to of us in the club are having troubles with it,it started with the air mixture screw O ring,then now it quits in the middle of the flight,im having problems tuning it,its becoming "A PAIN IN THE ....), )
is there something wrong with those engines?

thanks,[:@]
Old 08-13-2004, 07:10 AM
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Default RE: os 50 sx!!

I sure love mine but it's 2+ years old. Maybe there is a newer version that's got trouble. But like I said, mine ROCKS.
Old 08-13-2004, 08:12 AM
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Default RE: os 50 sx!!

What fuel are you running? What prop are you running? What type of flying to you do?

I have several buddies that run the OS .50 sx trouble free.....
Old 08-13-2004, 08:54 AM
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Default RE: os 50 sx!!

I currently have 4 50SX's and they all fly great. One is on a GP AT-6 Texan swinging a 12x8 ... very fast plane. One is on a H9 Cessna "experimental" swinging a 11x7 3-blade MA ... very fast plane. One is on a FuntanaS .40 swinging a 13x4 APC. And the 4th is on a SIG Ultimate FF Profile swinging a 12.25x3.75 APC. They all run CoolPower 15%. I don't think I've ever had one of them quit on me. Great engines .... I love 'em.
Old 08-13-2004, 10:16 AM
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Default RE: os 50 sx!!

im using power master fuel 15% castor synthetic mixture,on a fun fly the prop is 12.25x3.75 apc
Old 08-13-2004, 10:20 AM
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Default RE: os 50 sx!!

i forgot if anyone of u guys is using a tuned pipe on his engine,and what kind?

thanks
Old 08-13-2004, 10:22 AM
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Default RE: os 50 sx!!

Is the engine cowled? A lot of time in cowled application, the engines tend to overheat causing flameouts.
Old 08-13-2004, 10:55 AM
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Default RE: os 50 sx!!

no its not ,its out of the cowl
Old 08-13-2004, 11:12 AM
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Default RE: os 50 sx!!

Have you had much experience tunning engines? There is a wealth of information in the engine section here on rcu..
Old 08-13-2004, 04:14 PM
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Default RE: os 50 sx!!

Just as a test ... try coming out on the low end adjustment 1/4 of a turn. Because you have the engine on a Fun Fly, I am assuming you are flying at less than full throttle most of the time. Here are the steps that I use to adjust my engines:

* adjust the high end needle for max rpm
* richen (counter-clockwise) high end needle at least 3 clicks
* adjust low end so that the engine hesitates a little bit after idling for about 5 seconds
* lean (clockwise) low end 1/8 of a turn until you get a smooth transition from idle to WOT
* re-adjust the high end needle for max rpm
* richen (counter-clockwise) high end needle at least 2 clicks

After you have done this once, you should only have to adjust the high end needle on each flying day ... unless you change fuel percentages or brands. The 50SX is designed for high rpm use so it has a finer/smaller "sweet spot" than say a 46FX or 46AX.

One other thing to check is fuel foaming. You should not see any bubbles in your fuel line between the needle valve and the carb at any time ... other than during priming and starting. If you are getting bubbles in your line between the needle and carb ... your engine is leaning in flight and overheating. Profiles / Fun Flies are notorious for transmitting vibration through the fuse to the fuel tank. If you are getting foaming and can't make it go away ... richen a little on both needles. I have seen people fly for years that way.

You also mentioned a tuned pipe. If you are running a tuned pipe on this engine you should always run about 1/8 of a turn richer on the low end and at least 1 to 2 clicks richer on the high end. You want to adjust the engine on the rich side ... but still lean enough to "get on the pipe" smoothly. You can use the same procedure as I gave above ... just stay on the rich side of everything.
Old 08-13-2004, 07:32 PM
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Default RE: os 50 sx!!

Also dont forget this a ringed engine that should be slowly and very richly broken it, sputtering rich break-in may be needed for at least one gallon worth of fuel
Old 08-13-2004, 07:39 PM
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Default RE: os 50 sx!!

Can't say this will work for everyone but it is how I tune my engines.
Tim Mills wrote it.

Carburetor Adjusting 101

--------------------------------------------------------------------------------

Here's a scenario: Pilot takes off, plane's engine sounds great. After several minutes of flying, engine seems to lose power, sounds kinda "thin", pilot keeps flying. Engine continues to sag, now full throttle is very weak, pilot now understands that maybe this isn't gonna clear up. Engine dies (what a shock! ), pilot calls for deadstick landing overshoots, tears off landing gear, etc. Never seen this at your field, right?

Here's the way that *I* set mixture on non-airbleed carbed engines (90% of the engines out there fit this category, but the theory is similar for air-bleed carbs). First of all, understand that the high speed needle has its main effect from 3/4 to full throttle, and the low speed needle controls everything from idle up to 3/4 throttle. It thus makes sense to me to spend the biggest majority of my tuning time adjusting the needle that controls the largest portion of engine running, right? Also, remember that there is a proper air to fuel ratio (mixture) that allows the engine to run properly. Too much fuel is rich, and too little fuel is lean. We "richen" the mixture by adding more fuel (turning the needle out, or counter-clockwise), and we "lean the mixture out" by decreasing the fuel (turning the needle valve in, or clockwise).

I start the engine give it full throttle, and lean it to it's highest rpm (peak), then richen it by maybe a quarter turn. Then with the glow plug igniter still attached, I slowly close the throttle to an idle rpm. At the lowest rpm that the engine will still reliably run, I then remove the glow igniter. If the engine dies immediately, I know it's too rich, and I then lean out the LOW SPEED NEEDLE by 1/8th of a turn (don't touch the high speed needle). Start the engine again, (and this is important) give FULL throttle briefly to clear out excess fuel, then slowly close the throttle again. Remove the glow igniter, and this time it may run a little longer before it dies, so lean the low speed another 1/8th turn. Re-fire the engine, give a burst of full throttle to clear it out, and slowly close the throttle again. remove the glow igniter and now notice that the rpm DROPPED a bit when you removed the glow igniter, but the engine kept running. We're getting there. It's still too rich, and you'll prove that by opening up the throttle and hearing the engine "blubber" then die. That's because excess fuel has collected in the crankcase during the rich idle, and when you opened up the throttle, the excess was pulled into the cylinder, making it WAY too rich. Supposed you were on a landing approach, and decided to go around, you throttle up but the engine "blubbers" and then dies (another thing we haven't seen, right?). Yep, the LOW SPEED needle was still too rich, allowing excess fuel to collect in the crankcase, just WAITING on you to try to go around so it could "LOAD UP", blubber, and die!

Keep leaning the low speed needle down until it idles well, but now, when you open up the throttle, it HESITATES instead of BLUBBERS. When this happens, you've lean it down too far, so richen it up 1/16th of a turn and try again. You know you've got the LOW SPEED needle right when you can fire it up, remove the the glow igniter, and the rpm doesn't change AT ALL, and you can open the throttle up, and it doesn't blubber or hesitate, it just runs!

The final thing you do is re-adjust the HIGH SPEED NEEDLE, leaning it to it's highest rpm (peak) and then richening it up maybe 1/8th turn to give it a slightly rich mixture. We also know that the fuel mixture will change in flight when you point the nose up (harder for fuel to travel uphill) and also as the fuel level in the tank changes. In both cases, a leaner mixture results, so we actually need to set the mixture a bit further on the rich side to account for this. While the engine is running at full throttle, CAREFULLY pick the model up and raise the nose to at least a 45 degree angle while listening to the engine. If the engine sags a bit, then you'll need to richen up the high speed needle 1/16th turn. Try it again, and when you can point the nose up and the engine doesn't sag, but maybe shows a slight GAIN in rpm, you know you've got it right.

Now the engine will be happy, and chances are will reward you with reliable running. If you've got one of the few engines with an air bleed adjustment for low speed adjustment, the theory is the same, just refer to your manual to see how to richen and lean the low speed mixture.

Gotta go rest my typing fingers!
Tim
Old 08-13-2004, 09:35 PM
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Default RE: os 50 sx!!

Nice explaination Mike18....
Old 08-14-2004, 12:42 AM
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Default RE: os 50 sx!!

thank u guys for those long explenations a lot
Old 08-14-2004, 07:57 AM
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Default RE: os 50 sx!!

Nice explaination Mike18....
I can't take the credit...
Tim Mills wrote it.
Using this method I almost never touch my needle settings...I just fuel em up and fly.
I print it out and give it to new members in our club that ask me for advice on how I tune my engines.
Old 08-14-2004, 02:31 PM
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Default RE: os 50 sx!!

ORIGINAL: Mike18

Can't say this will work for everyone but it is how I tune my engines.
Tim Mills wrote it.

Carburetor Adjusting 101

--------------------------------------------------------------------------------

Here's a scenario: Pilot takes off, plane's engine sounds great. After several minutes of flying, engine seems to lose power, sounds kinda "thin", pilot keeps flying. Engine continues to sag, now full throttle is very weak, pilot now understands that maybe this isn't gonna clear up. Engine dies (what a shock! ), pilot calls for deadstick landing overshoots, tears off landing gear, etc. Never seen this at your field, right?

Here's the way that *I* set mixture on non-airbleed carbed engines (90% of the engines out there fit this category, but the theory is similar for air-bleed carbs). First of all, understand that the high speed needle has its main effect from 3/4 to full throttle, and the low speed needle controls everything from idle up to 3/4 throttle. It thus makes sense to me to spend the biggest majority of my tuning time adjusting the needle that controls the largest portion of engine running, right? Also, remember that there is a proper air to fuel ratio (mixture) that allows the engine to run properly. Too much fuel is rich, and too little fuel is lean. We "richen" the mixture by adding more fuel (turning the needle out, or counter-clockwise), and we "lean the mixture out" by decreasing the fuel (turning the needle valve in, or clockwise).

I start the engine give it full throttle, and lean it to it's highest rpm (peak), then richen it by maybe a quarter turn. Then with the glow plug igniter still attached, I slowly close the throttle to an idle rpm. At the lowest rpm that the engine will still reliably run, I then remove the glow igniter. If the engine dies immediately, I know it's too rich, and I then lean out the LOW SPEED NEEDLE by 1/8th of a turn (don't touch the high speed needle). Start the engine again, (and this is important) give FULL throttle briefly to clear out excess fuel, then slowly close the throttle again. Remove the glow igniter, and this time it may run a little longer before it dies, so lean the low speed another 1/8th turn. Re-fire the engine, give a burst of full throttle to clear it out, and slowly close the throttle again. remove the glow igniter and now notice that the rpm DROPPED a bit when you removed the glow igniter, but the engine kept running. We're getting there. It's still too rich, and you'll prove that by opening up the throttle and hearing the engine "blubber" then die. That's because excess fuel has collected in the crankcase during the rich idle, and when you opened up the throttle, the excess was pulled into the cylinder, making it WAY too rich. Supposed you were on a landing approach, and decided to go around, you throttle up but the engine "blubbers" and then dies (another thing we haven't seen, right?). Yep, the LOW SPEED needle was still too rich, allowing excess fuel to collect in the crankcase, just WAITING on you to try to go around so it could "LOAD UP", blubber, and die!

Keep leaning the low speed needle down until it idles well, but now, when you open up the throttle, it HESITATES instead of BLUBBERS. When this happens, you've lean it down too far, so richen it up 1/16th of a turn and try again. You know you've got the LOW SPEED needle right when you can fire it up, remove the the glow igniter, and the rpm doesn't change AT ALL, and you can open the throttle up, and it doesn't blubber or hesitate, it just runs!

The final thing you do is re-adjust the HIGH SPEED NEEDLE, leaning it to it's highest rpm (peak) and then richening it up maybe 1/8th turn to give it a slightly rich mixture. We also know that the fuel mixture will change in flight when you point the nose up (harder for fuel to travel uphill) and also as the fuel level in the tank changes. In both cases, a leaner mixture results, so we actually need to set the mixture a bit further on the rich side to account for this. While the engine is running at full throttle, CAREFULLY pick the model up and raise the nose to at least a 45 degree angle while listening to the engine. If the engine sags a bit, then you'll need to richen up the high speed needle 1/16th turn. Try it again, and when you can point the nose up and the engine doesn't sag, but maybe shows a slight GAIN in rpm, you know you've got it right.

Now the engine will be happy, and chances are will reward you with reliable running. If you've got one of the few engines with an air bleed adjustment for low speed adjustment, the theory is the same, just refer to your manual to see how to richen and lean the low speed mixture.

Gotta go rest my typing fingers!
Tim
Just a little ignorant question...

For 4-strokers, the process is the same?
Old 08-14-2004, 04:10 PM
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Default RE: os 50 sx!!

hi guys,

well thanks for all the advices but i guess that my engine needs new bearings,its been running for 1 and a half year[:-]
Old 08-14-2004, 09:08 PM
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Default RE: os 50 sx!!

Just a little ignorant question...

For 4-strokers, the process is the same?
EagleOne,
First thing, there are no ignorant questions...we all learn by asking questions and I think yours is a very good one.
Second thing, I don't know if this is how a four stroke is tuned because I don't run them yet.
Maybe someone else knows.
Old 08-14-2004, 10:43 PM
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Default RE: os 50 sx!!

It's basically the same thing for 4 strokers. I find the low end actually more important in a 4S. Seems it needs changed with the seasons, etc. Whereas my 2S seem to be set-and-forget for the most part. I'm moving toward all 4S cause I like 'em, but they are slightly more work.

One thing seems different, a 4S will run lean without as much indication. I run my 4S engines way richer than the 2S ones.
Old 08-15-2004, 04:08 PM
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Default RE: os 50 sx!!

Thanks a LOT!!

I got an OS 91 Surpass II w/pump, and this being my first 4-stroker, I am a little in doubt how to tune them. So, if it's like a 2S, then it will be no problem. Since they don't show obvious signs that they are being run lean, a tachometer will be of help??
It still needs to be broken-in, but information in advance is very nice....
Old 08-15-2004, 04:22 PM
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Default RE: os 50 sx!!

Yeah, I used to tach all my 4S. I couldn't hear them very well. Now that I am used to the sound, and because I run them very rich (I'm WAY over powered, so I don't need the full power), I don't need the tach anymore. But it's very good insurance. I would come off peak about 300 to 500 rpm. It's also interesting to see that you can lean it past peak and loose 500rpm without hearing it, or at least I couldn't.

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