Ok guys bear with me I'm sort of new at the RC's. I purchased a used century hawk with an OS 32sx-h eng. and airtronics rd6000, it has a mechanical gyro. It's in pretty good shape and I have had it running several times and have even hovered for 4-5 min. at about 4-5 feet with training gear of course. The person I purchased it from is from across the country but did say he had problems getting the eng to run consistent. Never did find out what fuel he was running but I've been using Sig champion Helli 15% nitro with 22% synthetic oil, it's double filtered before it reaches the fuel tank. Now to the problem, I can not get it to run consistent. I usually only have time to practice on sat or sun and it always starts right up the first time with inconsistent performance, sometimes good, sometimes it will die when I try to throttle up, sometimes it dies when it's hovering and running fine. Occasionally if I can catch it and hold it just above an idle for a minute or so it will be alright for awhile. Usually the longer it runs the worse it gets sometimes to the point where I can't get it to start til the next weekend. The longest I've had it run is about 10 minutes. Being as though I can only hover and not fly how do I go about setting or reseting the fuel and idle mixtures when I can't run it up to full throttle and any suggestions as to what else could be the problem would be greatly appreciated. Sorry for the long message but wanted to make sure I gave as much info as possible. Thanks

it sounds to me like its to lean.
turn the high end needle in ,but but dont crank on it.
then turn the needle out to 3 full turns and start from there with getting the tune set .
this is used and you dont know how much time is on the engine .
but give this a try.

That's what I'm sort of thinking but everything I've read talks about running it up to peak rpm to adjust, How do I do that when I'm not able to fly yet just, hover for a few minutes at 1/2 throttle. Iv'e heard about doing it without the blades but then do I remove the tail rotor blades too or can I just drop the counter gear away from the eng so it doesn't turn either.

just do the tuneing will your hovering.lift off listen to how the engine sounds and keep going from there.

Thanks Scott I'll try again this weekend and see what happens.

Cobra

Depending on how old the engine is you may want to inspect/replace the rubber o-rings on the carbs. If these things are leaking air the engine will be a bear to run/tune.

Also, is your helicopter experiencing any extreme vibration? If so that will introduce small air bubbles into the fuel line which will cause the engine to run too lean, and it will once again be a bear to tune. The solution here is to sort out the vibration, or get a header tank, or both.

Is the fuel tank pressurised from the muffler? Otherwise the tank will make a vacuum and starve the engine of fuel.

You shouldn't really have this type of hassle with the setup you have mentioned ie Hawk & OS.