Tuning at higher altitude

[Greatsteaks]

I live in the Denver Colorado area, 5000-6000ft. I fly RC helicopters and just got my first gasser heli, I know this is mostly a surface vehicle forum but maybe you guys can help me with some basic needle settings to start off with. I have a Zenoah g260rc engine with a Walbro 643 carb, I just ordered a 990 carb but the base settings should be the same. Base settings for my engine and carb at around sea level (info obtained from experienced heli engine tuners from everywhere except higher altitude locations) is around 1 3/8 max rich for the low needle And 1 3/8 max lean for the high needle. Can anyone from my altitude level give me some idea where I should start and where to expect to end up with my needles? Thanks

 

[MrFnisse]

There is an idiots engine tuning guide here on the forum. Do a search if you cant find it. I'm pretty sure no one here will be able to give you an exact needle setting since each engine differs somewhat. The engine tuning guide should guide you to a good setting.

 

[atom3624]

As stated, just follow the guide, but generally for non-forced induction, the higher you go, the less oxygen there is in the air, so you'll need to lean off.
Be careful you don't lean too far which will mean not enough oil's getting in to lubricate properly.
Possibly need to default to 25:1 if you're on 32:1 to ensure there's enough oil.
Al.