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Engine cutting


Tony j
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Hi all

wondering if anyone can throw some light onto this . The engine is running fine on the ground i.e ticks over ok, throttles up to max ok , pulls nicely when held vertical . I have no issue when flying, until I come in to land as I lower the throttle towards tick over the engine dead sticks . now I have been flying with this set up for weeks then all of a sudden I have this issue. any thoughts ?

Many thanks in advance

Kind regards

Tony

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Hi all

thank you so much for your advice will try all of these options.

Denis its a two stroke engine.

John have uped the clicks a couple of times and tried resetting the adustment in case it was moving too far but had not had issue before ,trouble is I am not good with engines it was a quite a while before i was able to tune them without help not sure I am that clever now but learning. changing the plug I will do next .

mowerman .

if engine is over cooling what is the thing to do for that

cymaz

will try the low speed needle and richen it slightly

I will report back as soon as I have sorted it no flying today sadly so may be next week weather permitting

Thanks all again

Kind regards

Tony J

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  • 2 weeks later...

I had a similar experience yesterday with two different engines.

I had set aside the morning to give some instruction to a beginner. The model we used was a Seagull Boomerang 2 which is normally powered by an Enya 50 SS but owing to a stripped thread I had fitted an Enya 45 which flew the model well enough but which struggled on take off. The Boomerang 2 has a fully sheeted wing and is probably heavier than most comparable trainers. Having flown it once I tried to get a few more revs out of it by adjusting the main needle. This provoked a series of engine cuts on the ground which I put down to my unfamiliarity with the engine. I resorted to my second trainer powered by an Irvine 40 which performed perfectly.

In the afternoon I flew my SLEC Fun Fly powered by an OS 40FP fitted with a Just Engines Super Quiet silencer. This cut out in the air and I had to land in a field of wheat. This engine has always been 100% reliable.

I will try stripping and cleaning the carburetters, replacing the glow plugs and flushing out the tank in the case of the Fun Fly; the Boomerang is brand new and has only had a few flights.

I am not usually a Needle Twiddler, once my carburetters have been set I tend to leave well-enough alone but it was hot here yesterday, over 30C. Do you think that would that have an effect on the engines?

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Hi all

Ok, all is sorted now , so I had a little play with the engine at home a good clean out of everything a slight adjustment of the low end needle ,which I must admit I don't like to mess with . changed the plug just for the sake of it , went flying yesterday not one dead stick anywhere , a nice tick over when coming in to land yes many thanks all .

Kind regards

Tony J

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Brilliant Tony, often just moving the needles dislodges the blockage.

The reason I asked was this 2 or 4 stroke, is that they breathe differently, the 2 stroke being more susceptible to pressure leaks from the backplate or bearings for instance. The 4 stroke just gets on with it and is usually fuel feed related when they get needle sensitive.

You got there, get flying now

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I flew on Saturday, temperatures between 28 and 35, when I called to a day. It played havoc with the motor, right lean. I am not a twiddler, a click here and there, if it sounds OK first start I leave well alone.

The motor, a reliable thing, was so far out I wondered if someone had given it a random alteration.

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Plugs are so good these days it’s easy to leave them in too long only to suffer gradual deterioration. A bad plug affects idle more than top end as at high rpm much more heat is generated so it’s much less likely “ the flame goes out”. Because of that I tend to change the plug a bit more often than really necessary on my favourite models. Obviously all the blockages etc can also be a factor but i do find that rare as I always clean fuel pipes before putting them into a fuel can plus filter fuel going into the plane. When I finish running an engine I also make a point of running the tank and engine dry to avoid any left fuel in the line. I don’t use fuel filters inside the plane as that’s another area that can slowly accumulate a fuel block. The fuel I use us model Technics synthetic with no castor so it doesn’t gum up carbs. I think Martin on this site mentioned once he had a bicycle pump with football inflator in his toolbox to help clear debris in carbs... that sounds a good idea.

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I flew Saturday and didnt encounter any issues. The Laser petrol in my pulse and my trusty saito 45 in my nieuport 17 both performed well.

One thing to remember in hot weather is that cooling performance is obviously reduced, so even with correct tuning (tuned for max rpm) you may not be able to push the engine as hard as you normally would before it gets too toasty. The inclusion of the occasional high speed dive with the engine close to idle and reduced full throttle time will do wonders for keeping the engine cool.

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Mid to high 20's C is not "very hot", just warm, and nighttime temperatures have been mid to low teens, which is cool; so average 24-hour temperatures have been barely warm. The rest of the world at lower latitudes is generally way warmer. Modellers and model engines cope fine further south in Europe and in the southern US etc. Engines need only mild adjustments to needle valves. Take a look at temperature maps for other parts of the world.

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Posted by Tim Harris 1 on 02/07/2018 10:18:34:
I think Martin on this site mentioned once he had a bicycle pump with football inflator in his toolbox to help clear debris in carbs... that sounds a good idea.

Not a football adapter - a nozzle which I can fit a length of fuel pipe to. I attach it to the fuel inlet and give it some swift pumps with the needle removed - replace the needle a few turns to just seal the O ring and pump again, which seems to resolve most blockage problems.

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Posted by Don Fry on 02/07/2018 12:58:50:

John, I can't help thinking you have to be right. My engine is uncowled . I must have a phantom needle twiddler

Not necessarily. Many engines cannot dissipate all the heat they create at full power if the outside temperature is above a certain threshold. While i agree that 30c is not outrageously hot it is slightly unusual for the UK so any engine set up to work in our normal frigid temperatures is likely to protest now its nice and toasty

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Posted by Jon - Laser Engines on 02/07/2018 14:59:33:
Posted by Don Fry on 02/07/2018 12:58:50:

John, I can't help thinking you have to be right. My engine is uncowled . I must have a phantom needle twiddler

Not necessarily. Many engines cannot dissipate all the heat they create at full power if the outside temperature is above a certain threshold. While i agree that 30c is not outrageously hot it is slightly unusual for the UK so any engine set up to work in our normal frigid temperatures is likely to protest now its nice and toasty

Fully agree. I have been flying in hotter conditions, but it was "normal weather" (south of Spain in summar) so all our engines were setup to cope with it. This weather is quite unusual for these latitudes so I guess that it is common to face issues with engines now...

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