If the idle mixture setting is turned in a lot, then the high-speed needle will tend to be well open. However, if the idle needle's turned out a lot, then the high-speed needle will usually be at 1-3/4 to 1-1/2 turns out from closed when leaned to just rich of peak RPM. If the needle must be turned in a LOT, as your's is, then it's likely you have damage to the needle and the needle seat in the carburetor. This can be confirmed by removing the needle and looking at the pointy part. You'll see a polished ring around it. That means that it's been beating against the needle seat due to vibration. You'll need a new carburetor body and a new needle to make a fix.