Is the fuel/plug too hot for my engine.
08-09-2018, 11:59 PM
#1
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Is the fuel/plug too hot for my engine?
Returning to the hobby after a 10 year hobby and for now picking up with the aircraft I have in storage, a 46 sized palne and a 50 sized helicopter.
Thought I only want to carry one type of fuel around with me so I have gone with 20% nitro (18% synthetic oil) which is what the helicopter needs.
But I wonder whether that is too hot for my 46 sized sports planenas I do get some funny behaviour?
The 46 is a well run in engine. It starts first flick, but sometimes the tuning seems to wander and the running is inconsistent. Sometimes it will idle smoothly and pick up great, other times it will idle smoothly but then splutter and cut on pick up. And on a couple of occasions I have had it when the engine is racing (like on half throttle) with the throttle at idle - on those occasions the throttle cut has noneffect and I have to pinch or remove the fuel line to stop it.
Fuel is new as is the plug which is an Enya No 3.
Cheers,
Nigel
Thought I only want to carry one type of fuel around with me so I have gone with 20% nitro (18% synthetic oil) which is what the helicopter needs.
But I wonder whether that is too hot for my 46 sized sports planenas I do get some funny behaviour?
The 46 is a well run in engine. It starts first flick, but sometimes the tuning seems to wander and the running is inconsistent. Sometimes it will idle smoothly and pick up great, other times it will idle smoothly but then splutter and cut on pick up. And on a couple of occasions I have had it when the engine is racing (like on half throttle) with the throttle at idle - on those occasions the throttle cut has noneffect and I have to pinch or remove the fuel line to stop it.
Fuel is new as is the plug which is an Enya No 3.
Cheers,
Nigel
Last edited by nheather; 08-10-2018 at 12:08 AM.
08-10-2018, 04:04 AM
#3
Glow engines are notoriously fickle about temperature and humidity. The first two items may just be that - some days the mixture is right on, others just a hair off. Acceleration problems (idle, sputter, and cut) are due to the low end being off. Try this: Run the engine for a bit, to get it fully warmed up. Bring it to idle, and let run for a bit to stabilize. Using a forceps, needle nose pliers, or similar, pinch the fuel line that goes to the carb. If it dies very quickly, you are too lean at idle. If it picks up in rpm, and then dies, you are too rich. You should get a few seconds of even running before it goes into stumble and quit due to lack of fuel. For the idle adjustment, the good news is that you shouldn't have to adjust it again, unless you change fuel types or prop type/size.
The same process can be followed when running at full throttle for the main needle valve, but usually the "point it straight up" method is easier. That needle may need a couple of clicks in one direction or the other depending on the weather.
For the third issue (engine racing at idle) - that seems to be an issue with the carb not operating correctly. Most likely a servo/linkage issue. Can you actually see the carb close when it happens, or are you just trusting that moving the stick down is closing the carb? Old, worn engines can have gum in them that makes the carb barrel very sticky, or it may be some damage to the barrel. Or maybe the pushrod is bowing/flexing/sticking. Or the servo not operating correctly. Sometimes the vibration of the engine is enough to overcome the resistance, and all operates correctly, sometimes it goes opposite and something sticks - preventing the carb barrel from moving. Depending on the engine, sometimes the barrel sticks, and the actual arm on the engine still moves (stripped), so check that, too. Make sure the pushrod has virtually no ability to flex/bend, it has no opportunity to bind up, and there is no slop in the connections - that alone can contribute to variability in getting the engine to run correctly.
Of course, make sure all bolts on the engine are tight - air leaks can play havoc with it running right.
Report back in more detail if the above doesn't help.
The same process can be followed when running at full throttle for the main needle valve, but usually the "point it straight up" method is easier. That needle may need a couple of clicks in one direction or the other depending on the weather.
For the third issue (engine racing at idle) - that seems to be an issue with the carb not operating correctly. Most likely a servo/linkage issue. Can you actually see the carb close when it happens, or are you just trusting that moving the stick down is closing the carb? Old, worn engines can have gum in them that makes the carb barrel very sticky, or it may be some damage to the barrel. Or maybe the pushrod is bowing/flexing/sticking. Or the servo not operating correctly. Sometimes the vibration of the engine is enough to overcome the resistance, and all operates correctly, sometimes it goes opposite and something sticks - preventing the carb barrel from moving. Depending on the engine, sometimes the barrel sticks, and the actual arm on the engine still moves (stripped), so check that, too. Make sure the pushrod has virtually no ability to flex/bend, it has no opportunity to bind up, and there is no slop in the connections - that alone can contribute to variability in getting the engine to run correctly.
Of course, make sure all bolts on the engine are tight - air leaks can play havoc with it running right.
Report back in more detail if the above doesn't help.
08-10-2018, 04:51 AM
#4
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Glow engines are notoriously fickle about temperature and humidity. The first two items may just be that - some days the mixture is right on, others just a hair off. Acceleration problems (idle, sputter, and cut) are due to the low end being off. Try this: Run the engine for a bit, to get it fully warmed up. Bring it to idle, and let run for a bit to stabilize. Using a forceps, needle nose pliers, or similar, pinch the fuel line that goes to the carb. If it dies very quickly, you are too lean at idle. If it picks up in rpm, and then dies, you are too rich. You should get a few seconds of even running before it goes into stumble and quit due to lack of fuel. For the idle adjustment, the good news is that you shouldn't have to adjust it again, unless you change fuel types or prop type/size.
The same process can be followed when running at full throttle for the main needle valve, but usually the "point it straight up" method is easier. That needle may need a couple of clicks in one direction or the other depending on the weather.
For the third issue (engine racing at idle) - that seems to be an issue with the carb not operating correctly. Most likely a servo/linkage issue. Can you actually see the carb close when it happens, or are you just trusting that moving the stick down is closing the carb? Old, worn engines can have gum in them that makes the carb barrel very sticky, or it may be some damage to the barrel. Or maybe the pushrod is bowing/flexing/sticking. Or the servo not operating correctly. Sometimes the vibration of the engine is enough to overcome the resistance, and all operates correctly, sometimes it goes opposite and something sticks - preventing the carb barrel from moving. Depending on the engine, sometimes the barrel sticks, and the actual arm on the engine still moves (stripped), so check that, too. Make sure the pushrod has virtually no ability to flex/bend, it has no opportunity to bind up, and there is no slop in the connections - that alone can contribute to variability in getting the engine to run correctly.
Of course, make sure all bolts on the engine are tight - air leaks can play havoc with it running right.
Report back in more detail if the above doesn't help.
The same process can be followed when running at full throttle for the main needle valve, but usually the "point it straight up" method is easier. That needle may need a couple of clicks in one direction or the other depending on the weather.
For the third issue (engine racing at idle) - that seems to be an issue with the carb not operating correctly. Most likely a servo/linkage issue. Can you actually see the carb close when it happens, or are you just trusting that moving the stick down is closing the carb? Old, worn engines can have gum in them that makes the carb barrel very sticky, or it may be some damage to the barrel. Or maybe the pushrod is bowing/flexing/sticking. Or the servo not operating correctly. Sometimes the vibration of the engine is enough to overcome the resistance, and all operates correctly, sometimes it goes opposite and something sticks - preventing the carb barrel from moving. Depending on the engine, sometimes the barrel sticks, and the actual arm on the engine still moves (stripped), so check that, too. Make sure the pushrod has virtually no ability to flex/bend, it has no opportunity to bind up, and there is no slop in the connections - that alone can contribute to variability in getting the engine to run correctly.
Of course, make sure all bolts on the engine are tight - air leaks can play havoc with it running right.
Report back in more detail if the above doesn't help.
When it is racing, the stick is low, the throttle is open a tiny bit as per design, and when I hit the throttle cut the barrel closes completely - but the engine races. Possibly air getting in but remember it doesnt do it that often and with the barrel closed it shouldnt be bringing in any fuel either should it - but it will continue until the tank is dry if I let it.
Id like to replace all the O Rings but it is a Magnum XL 46, and you cant get spares anymore. Maybe the same as an ASP - Im investigating that.
Cheers,
Nigel
08-10-2018, 10:56 AM
#5
Yes, that is the issue. As you guessed, probably an o-ring that is faulty. It seals most of the time, but not all. It's been a long time since I had a Magnum, so I can't remember the carb design. If it has o-rings on the barrel of the carb, and the local hardware store doesn't have any of the same size, you could try to tighten it up by putting a few wraps of thread next to it, in the groove it sits in. Just enough to make it compress very, very slightly so it begins to bulge out of the groove. Too much, and the barrel will either not rotate easily, or it will be hard to even get the barrel back into the carb. If there is one on the carb bottom, that seals where the carb goes into the engine, the leak could also be there. Same fix, although as long as you get good compression of the o-ring between the carb and the engine, size is not critical, so you should be able to find one locally.
08-10-2018, 11:48 AM
#6
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Pretty sure they were OS FX copies, like ASP and SC. Only ASP exist now. I’ll order the ASP needle and the carb o-rings - only a few dollars so not much lost if the size is wrong.
Cheers,
Nigel
Cheers,
Nigel
08-10-2018, 06:47 PM
#7
With the racing, 90% of the time it idles nicely and if I hit the throttle cut it will stop instantly. It is only 2 or 3 times that I have seen it racing. The carb is set to be slightly open at low stick using the endpoint on the transmitter. I also have the thottle cut to close the throttle completely.
When it is racing, the stick is low, the throttle is open a tiny bit as per design, and when I hit the throttle cut the barrel closes completely - but the engine races. Possibly air getting in but remember it doesnt do it that often and with the barrel closed it shouldnt be bringing in any fuel either should it - but it will continue until the tank is dry if I let it.
Id like to replace all the O Rings but it is a Magnum XL 46, and you cant get spares anymore. Maybe the same as an ASP - Im investigating that.
Cheers,
Nigel
08-14-2018, 11:44 AM
#8
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Hi!
20% is too mutch!!!! Your engine will run perfect on just 0-5% nitro
Too much nitro and you will have difficulties setting the needle and the engine will run very erraticly and answer to throttle very badly.
20% is too mutch!!!! Your engine will run perfect on just 0-5% nitro
Too much nitro and you will have difficulties setting the needle and the engine will run very erraticly and answer to throttle very badly.
08-15-2018, 12:44 PM
#10
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Hi!
And a perfect glow plug for your .46 engine is a Nova Rossi (or Rossi) 3 or 4 plug or...an OS 8 or Enya 3 ...if you run it on 0-10% nitro.
anything over 5% niro on this engine is just a waste of money.And using more than 15% nitro will make it run very bad!
And a perfect glow plug for your .46 engine is a Nova Rossi (or Rossi) 3 or 4 plug or...an OS 8 or Enya 3 ...if you run it on 0-10% nitro.
anything over 5% niro on this engine is just a waste of money.And using more than 15% nitro will make it run very bad!
08-16-2018, 11:27 AM
#13
My Feedback: (1)
it was just a suggestion, I have an OS 61FX and it was bought new in 2004 (want to buy it ?), it had sat 6 years, I started it, it needs new O-rings, besides, that's the hobby, things just happen.. too add I have seen a Super Tiger run on too much nitro, it ran great at idle and lower RPM, but once around (???) say, 60% throttle and above it ran terribly bad, it could not be tuned out, once changing to a lower nitro count, fixed it in a snap
Jim
Jim
08-17-2018, 10:03 AM
#14
Let's not loose sight that the issue was one of continuing to run, even with the carb almost closed, on occasion. High nitro would make it run poorly, which is not the case - he reports that it seems fine when it does behave normally. A bad seal somewhere allowing air to enter when not wanted would seem to be the most likely explanation. Of course, too high nitro might lead to overheating and scoring the piston...but then it would run poorly all the time. So while lower nitro is better, it is not the cause of the main issue.
10-12-2018, 11:53 AM
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Let's not loose sight that the issue was one of continuing to run, even with the carb almost closed, on occasion. High nitro would make it run poorly, which is not the case - he reports that it seems fine when it does behave normally. A bad seal somewhere allowing air to enter when not wanted would seem to be the most likely explanation. Of course, too high nitro might lead to overheating and scoring the piston...but then it would run poorly all the time. So while lower nitro is better, it is not the cause of the main issue.
