Well I can't speak to what your instructor has done with it, but the instructions on my NexStar told me about the plastic stop on the needle valve that they have pre-installed from the factory that will allow us some adjustment travel but keep us in a range that will not be too rich, or too lean. I ran mine for a few minutes to warm it up then slowly leaned it a little at a time until I got a nice smooth idle, & good transition. It ended up just about at the leanest position possible with the stop on it. Since I aint no engine tuning Guru I thought it sounded like a good safety feature to me so I left it on & it worked fine for me. Did you or your instructor remove the tuning stop?