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Super Tigre .90 steady running problems.
Hello, I have a new Super Tigre .90, 2 stroke engine, using Morgan Fuel cool power 15% nitro, with a 12x8, 2 blade master airscrew prop.Here is the problem, after break in the engine starts quick, runs nice and have a nice idle to high power transition and viceversa, but after a few minutes( about 3 to 4 of running), if throtle is moved all back to iddle, the engine just stop, and sometimes when letting it running in iddle, and throtle is moved to high power the engines performs well, then moved throtle back to iddle, and works nice, but then moved to hight throtle again and then stops.In other words, the engine stops VERY OFTEN( after a few minutes ), when in idle and then moved to hight power setting, or when in high power then throtle back to idle.I have tried medium-hot and hot spark plugs, idle screw and high neddle settings, looking for leaks, clooging, etc. but no effective results.We fly at sea level, normally (29 to 34) *C and medium humidity enviroment.Also, re-check and re-assembly of the carburetor, changing position of the spray bar, but still no results.If I start the engine and I let it run at idle, it runs continiously, and the same applies if engine is running at high power setting.The problem comes when changing power settings between idle and high power.I also re-check all screws on engine as well as back plate.I am using a pitts muffler.
What can be wrong with this engine?, Has any body experienced something like this? Thanks for any help. Isaias G. |
RE: Super Tigre .90 steady running problems.
G'day Mate,
Just a typical Super Tigre, rich midrange. |
RE: Super Tigre .90 steady running problems.
ORIGINAL: lechuza ...I have a new Super Tigre .90, 2 stroke engine, using Morgan Fuels Cool Power 15% nitro... Super Tigre engines are designed in Italy... Nitro is expensive in Europe and they are optimized to run on 0-5% nitro. Go to 5% and use fuel with some castor oil in it, like Morgan's Omega (not their all-synthetic 'CruelPower'). This will allow you to close both fuel controls somewhat and avert the rich mid-range Alan is referring to. The prop you are using is rather small too... A 13x8, or 14x6 would be better. |
RE: Super Tigre .90 steady running problems.
I would agree with Dar %100. I run a 13x8 on mine 10% nitro. Since you disassembled the carb I'm assuming you are adjusting the idle mixture. I never had a ST (or any engine for that matter) that didnt require idle adjustment after break in. In one case I worked with a students ST 90 for about an hour with no progress. As a last ditch effort, I put the stock muffler off mine onto his and it started to run fine. We adjusted it to get it perfect, then put his muffler back on. Went back to the same problem. Bad muffler in his case. It was not an issue with pushing it in too far on the exhuast manifold. The only one I've ever seen in all these years. It would be a shot in the dark in your case.
Edwin |
RE: Super Tigre .90 steady running problems.
My .90 supertigre runs great on Omega 15% and a 15x4 APC w prop.
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RE: Super Tigre .90 steady running problems.
That prop (12x8) is way too small for this engine. Try a 14x8. Mine runs great with zero nitro and somewhat more load. This might help you.
Misterpanda |
RE: Super Tigre .90 steady running problems.
Dave,
My 90 also runs great on 15% Byrons, the key is Castor oil I think as the same engine runs just as well on 10% with Castor. After several gallons the engine just gets better. |
RE: Super Tigre .90 steady running problems.
ORIGINAL: lechuza Hello, I have a new Super Tigre .90, 2 stroke engine, using Morgan Fuel cool power 15% nitro, with a 12x8, 2 blade master airscrew prop.Here is the problem, after break in the engine starts quick, runs nice and have a nice idle to high power transition and viceversa, but after a few minutes( about 3 to 4 of running), if throtle is moved all back to iddle, the engine just stop, and sometimes when letting it running in iddle, and throtle is moved to high power the engines performs well, then moved throtle back to iddle, and works nice, but then moved to hight throtle again and then stops.In other words, the engine stops VERY OFTEN( after a few minutes ), when in idle and then moved to hight power setting, or when in high power then throtle back to idle.I have tried medium-hot and hot spark plugs, idle screw and high neddle settings, looking for leaks, clooging, etc. but no effective results.We fly at sea level, normally (29 to 34) *C and medium humidity enviroment.Also, re-check and re-assembly of the carburetor, changing position of the spray bar, but still no results.If I start the engine and I let it run at idle, it runs continiously, and the same applies if engine is running at high power setting.The problem comes when changing power settings between idle and high power.I also re-check all screws on engine as well as back plate.I am using a pitts muffler. What can be wrong with this engine?, Has any body experienced something like this? Thanks for any help. Isaias G. --------------- The engine needs to be broken-in if it is fresh out of the box and new. Idling, transition and such will improve as the engine begins to find its final fit and not one second before. Put the engine on a test stand that is well up off the ground, so that it cannot ingest dust and grit from the ground. Fit it with the present propeller (that has been balanced). Rig the throttle for wide open operation. Start the engine and set it to run very rich. So rich that it stutters (four-strokes) for a couple tanks of fuel (16 oz. tanks of fuel). Repeat with the mixture (high speed - big needle) adjusted slightly leaner with the engine just two-stroking, but not leaned out. Run three or four more tanks with the throttle fully open. Yes, it sounds like a tremendous waste of fuel. In truth, it will be the best fuel you will ever flow through that engine. The engine will most likely be ready to fly and tune to perfection at this point. NOW you can adjust the idle and transition. Always run the engine on the rich side (more fuel) of peak and it will last you many years. See if your LHS (Local Hobby Shop) will begin stocking Omega fuel instead of just Cool Power. Omega offers some protection from accidental lean runs. Also, two-stroke model engines do not benefit from a lot of nitro the same way that four-stroke model engines do. Save some money and buy 5% Omega. Your engine and wallet will thank you. Ed Cregger |
RE: Super Tigre .90 steady running problems.
The ST 90 will run and transition very well if setup properly. Just keep working with it and you will get there. I does take some break-in to get it going well but mine was bolter right on out of the box and ran and runs great.
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RE: Super Tigre .90 steady running problems.
I've had them that way too, Bob. But it is far rarer than having to break them in properly.
One of the reasons that Super Tigre prices are so much less expensive than OS is because the level of fit and finish is not the same. This is good as it gives the modeler a chance to get familiar with the engine before attempting to fly it. For many folks, this will be their first exposure to a glow engine. Trying to figure it out in the air isn't the best of strategies. Then again, we are each entitled to our opinions. Opinions that have been formed according to our own experiences. Such is life. Ed Cregger |
RE: Super Tigre .90 steady running problems.
Mine was exactly like that also, about half way through the first tank of fuel it was running like a top. Idled nicely, perfect transititon and it settled about 500 off peak with a 13x6 apc prop. It was running so well I decided to fly the plane (World Models 60 sized Chipmunk). I have never had an engine of any brand run so well on its first tank.
Been a jewel ever since, and I normally run much more expensive motors. |
RE: Super Tigre .90 steady running problems.
Hello, and thanks all for your advises.Well, I have just tried a different fuel, the Morgan fuel Omega castor/synthetic engine fuel 5%(red) and the engine runs nice, no more stops as explained in my post, just a couple but due to needle adjustments, and excellent idle to high power transition and viceversa.It is very strange, because a friend of mine have a model with the same engine(ST .90), and he is using synthetic model engine fuel of this same brand and with 15% nitro(Green-the same fuel I was using before), but he never had engine problems like mine, also he is using the muffler that comes with the engine and I am using a Bisson pitts muffler, I don't know if a muffler could affect fuel type to be used in an engine.Anyway, everything in so far well, so I only have to fly the model to see the moment of truth.
Thanks again, Isaias G. |
RE: Super Tigre .90 steady running problems.
You may not have enough back pressure with the Pitts muffler. Try it with one of the outlets pluged.
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RE: Super Tigre .90 steady running problems.
Something to consider, I like a slimline large volume pitts muffler for my ST90. Gives it a nice deep growl which sounds great. Never have any problems with it. I dont know about other pitts type mufflers.
Edwin |
RE: Super Tigre .90 steady running problems.
ORIGINAL: daven My .90 supertigre runs great on Omega 15% and a 15x4 APC w prop. |
RE: Super Tigre .90 steady running problems.
Hi!
Seem like typical "To much nitro" to me! All old , pre Chinese Super-Tigres were made to run on low quantities of nitro. That means 0-5% nitro and Not 15%. 12x8 is also a too small prop in most sport airplanes. You should try a 14x6 instead or a 15x4 or 15x6, APC of course.. I run a 15x4 APC on my MVVS 15cc engine in my Great Planes GEE BEE R-2 and that is the perfect prop for that airplane. |
RE: Super Tigre .90 steady running problems.
My G90 runs absolutely perfectly on 15% Omega, 14-6 master airscrew, Slimline pitts muffler with the outlets pinched to increase the high needle sensitivity. It will run with them open, but I like the security of knowing that it's not going to lean out on me. It cost me 1000 rpm on the tach, but that's fine because I'm flying a 60 size plane with a 90 on it.
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RE: Super Tigre .90 steady running problems.
ORIGINAL: Not24 My G90 runs absolutely perfectly on 15% Omega, 14-6 master airscrew, Slimline pitts muffler with the outlets pinched to increase the high needle sensitivity. It will run with them open, but I like the security of knowing that it's not going to lean out on me. It cost me 1000 rpm on the tach, but that's fine because I'm flying a 60 size plane with a 90 on it. That is because you are running it so rich that you are loosing any advantage the higher nitro may give you... It is like running your high compression, high performance car on regular... The knock-sensor circuit allows this, but will never reach its full potential... The counterpoint is that higher nitro also costs more unlike regular gasoline. |
RE: Super Tigre .90 steady running problems.
ORIGINAL: DarZeelon ORIGINAL: Not24 My G90 runs absolutely perfectly on 15% Omega, 14-6 master airscrew, Slimline pitts muffler with the outlets pinched to increase the high needle sensitivity. It will run with them open, but I like the security of knowing that it's not going to lean out on me. It cost me 1000 rpm on the tach, but that's fine because I'm flying a 60 size plane with a 90 on it. That is because you are running it so rich that you are loosing any advantage the higher nitro may give you... It is like running your high compression, high performance car on regular... The knock-sensor circuit allows this, but will never reach its full potential... The counterpoint is that higher nitro also costs more unlike regular gasoline. By the way, I don't over richen the engine by any means. I just stay about 800 rpm on the rich side of peak, or in other words, a noticeable drop in rpm from peak by ear. That's what I've always done. |
RE: Super Tigre .90 steady running problems.
ORIGINAL: Not24 Say what you want about the high nitro being a waste and the engines are not designed for it. I'm not buying into that theory. I've done the flight testing to prove that the 15% works the best. I could lean my engine out more to get more performance, but I really don't need to. I only use full throttle while going vertical, and I know I'm nice and rich all the way up to 1000 feet. I use 15% in all my engines, because they all run better on it. By the way, I don't over richen the engine by any means. I just stay about 800 rpm on the rich side of peak, or in other words, a noticeable drop in rpm from peak by ear. That's what I've always done. I am not selling you anything, so I could not care less is you are not buying... But... You are already paying... through your nose! Running your engine 800 RPM rich of peak, is very much over-richening! It would typically make a .91 engine output similar power, to its .61 counterpart. On the same-size prop, a bored and stroked .91 engine, making ~40% more HP would typically be spinning the prop ~1,000 RPM faster than its .61 sibling. Your plane will fly the same with the ST .61. So, you are paying for a .91 engine, but actually getting .61 performance out of it... And wasting a lot of fuel on nothing flat... A good investment?? Will your .91 engine last any longer on such a rich mixture? No way, Jose. The extra oil it is getting is just being wasted, with all the extra fuel you are pouring into it. The only added value of running an engine richer than max, is that it reduces the chance of having it run TOO lean. It is a safety precaution that should be kept to the minimum necessary. With the needle acting as the ignition timing control in all glow engines, running your engine rich will retard the ignition, thus allowing a less tolerant fuel (i.e. higher nitro) to be run in it. And as to compression ratios and percentages of nitro in the fuel... It is well known to nearly all members here that engines made by prominent European manufacturers, like MVVS, Moki/Mark, Rossi, Novarossi (and until lately also Webra) have higher compression ratios, than OS and clones, K&B, TT, Etc.. These engines are designed to fully exploit the high octane number of methanol, by having a considerably higher C/R. Nearly all trouble users encounter with these engines, are the direct result of trying to run them on too much nitro... High nitro fuels are intolerant of high compression... These stubborn people try to blame their engines, when they should really start to bang their heads against the wall, being the only guilty party... Fox, BTW, also designed most of their engines to run on just 5% nitro. As to engines running better on 15%... More nitro gives you a wider acceptable needle range, because it has a stoichiometric range of 2.5:1 - 0.5:1. So, if your spare time is so precious that you do not have enough time to properly adjust your engine before flying, a fuel that allows the engine to run at nearly any reasonable setting, may get you to make such a remark. ...But pros do take time to adjust their engine for the fuel they are running. With your remark on not buying that theory, you are sounding like someone who would run his new Lamborghini on unleaded regular, instead of 104 octane Super that it needs... |
RE: Super Tigre .90 steady running problems.
Game, set and match! :)
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RE: Super Tigre .90 steady running problems.
I tend to run my engines on the lowest nitro% I can get away with and still get good performance. 5% Omega has been what I've always run in my ST G and S-90's. My LHS sells more 15% fuel than anything else to the sportflyers. I have to ask them to get me a case of 5% when they make the next order because they won't stock it.
It was not long ago that 10% was the standard fuel, and now it is 15%. Will 20% be the norm in a few years? |
RE: Super Tigre .90 steady running problems.
Clearly bigger is better out your way...
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RE: Super Tigre .90 steady running problems.
DAR, You can throw around all the engineering and physics you want. The real world tests prove that 15% works best in SuperTigre engines. I've never seen a 61 turn a 14-6 prop at 12000 rpm. I think you need to let the facts speak for themselves and not try so hard to prove yourself to people. The difference in price for 15% over 5% is negligible. It doesn't change the amount of time I have to save to buy a case of fuel. Implying that I don't know how to adjust my needles is just a little too much to take. By the way, I posted to this thread to help out the poor guy with engine troubles. I believe I gave him good advice. It will be up to him to decide whether or not he should listen to me. |
RE: Super Tigre .90 steady running problems.
Not24,
I think you had better check out that tachometer you are using... Spinning a 14x6 (Master Airscrew, I presume) at 12,000 RPM, requires that the engine produce 2.14 HP... On your plugged-up Slimline™ Pitts muffler... Plainly, it cannot make such power. And you are admittedly running the engine ~1,000 rich of peak... Are you saying your ST.91 can get to 13,000 RPM (2.72 HP) on this prop and muffler, peaked out??? I do not think so... Please read [link=http://www.supertigre.com/engines/supg0235-man.html]this MAN engine review[/link] by Mike Billinton, to see what I am talking about. Please note the fuel used, BTW. And, as to props, some .61 engines can spin very heavy props... Notable are the OS.61FS Hanno (specified 12x12, which is like a 14x6 load-wise) and MVVS (spins a significantly heavier 13x9 APC as a matter of course). |
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