Coughing OS50 hyper

[wadders]

hello all, i know im been a proper pain with all my questions but i dont have anyone else to ask!
I have tuned my engine to the point where its not overheating not running too rich but i still get the "ODD" twitch from the tail every now and then.........is it the engine coughing if so is it too rich or lean on the high end or the low end????????????????????????????????

Many thanks

[waveydavey]

I wouldn't worry about it too much, you might be able to richen the bottom end up slightly. This may help, it has with some but it never made any difference to me so I just ignore it, it's down to the return pressure wave from the pipe being out of sync with the firing of the engine.

Just out of interest where are your needles at the moment.

[wadders]

Well.... The main is around 2 turns out I think and the low end is about 2 o clock........

[waveydavey]

If you don't mind me saying your much too lean on the bottom in my experience and far too rich on the top end. Try re-setting both needles, go with 12 O'clock on the idle needle, you may be able to richen this up slightly in order to get rid of the squeaking from the pipe and the top end, again in my experience in this weather should be around 1 and 1/4 to 1 and 1/8. This is with 20% fuel. Does it give any power at 2 turns out?

[wadders]

Hmmmm, I will do that...... It seems to have allot of grunt but in saying that I'm use to a raptor 30 so maybe haven't seen the potential of the 50 hyper yet. The engine doesn't feel very hot after flying so maybe it's too rich like u say. As you can probably tell I'm pretty new at the sport so still trying to muddle through it all......

[waveydavey]

What pipe are you running, and is the engine new? If brand new then you may want to leave it on the rich side but definitely get the idle needle back to stock settings.

[wadders]

The pipe, I'm not sure I didn't buy it new........... Here's a pic of it.....ImageUploadedByTapatalk1307035764.516263.jpg

[waveydavey]

Looks like a Zimmerman, are you running the engine in or is it second hand too. Do you know it's history, was it ran in well etc

[smokingtommy]

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[coolice]

Hey.

I've seen this quite a lot in the older generation Hypers, basically the tail twitch your seeing accompanied by the cough or change of sound in the exhaust note is due to the engine being too lean in the mid range. This is a known problem with the OS 50 Hypers, as unlike the newer 55's with 3 needle carbs, you cannot easily adjust the mid range to counter-act the lean point brought about by tuning the low & high properly.

The trick with the Hypers to fix the rough mid range is to run the idle needle on the rich side, in most cases this produces quite a lumpy idle and if the model is sat for any length of time idling away then it can choke up and quit on throttle up. But the end result of running a richer idle is an engine which runs perfectly smooth throughout the rev range, throttles nicely to keep up with fast changes in power demands and ultimately doesn't pop & fart in the hover.
.

[wadders]

So, if I'm flying in idle up and say for example the throttle is at 50% will the low end needle setting still effect the mixture????

[coolice]

So, if I'm flying in idle up and say for example the throttle is at 50% will the low end needle setting still effect the mixture????

Hey buddy.

Yes, essentially. The low end needle has more of a bearing on how the idle mixture is than the high end needle, ultimately its still a balance between the two as if the top ends too lean no amount of richness on the low end needles going to compensate for it.

I haven't read if you are using a govenor or not, but without any major pitch loading you'll probably find the govenor is keeping the carb open in or around the mid range point to maintain a sensible head speed. It's only when you add load to the head that rpm needs to increase and the carb enters a point at which the mixture setting is better matched with the correct air/fuel ratio and the popping goes away.

As I'm sure you know many factors effect needle settings, plug type, fuel used and ambient temperature, but once you've hit the sweet spot normally its only the main needle requiring the odd click here or there from time to time.

Exhausts play a big part to, Zimmermans are quite good from memory but their construction material also changes tone of noise it gives out which can add to the confusion in setting up.
.

[electricsceadu]

for coughs and colds try

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