Factory settings are 1.5 turns out for both the low end and the high end with the regulator screw flushed with the engine casing. These settings are stated in the instruction manual. The engine should run fine at these settings. Tuning a YS requires some brain power, so you got to know what you are doing and can't blindly turn the needles. BTW, I've been using the same F plug in my YS 110 for close to three years now. In fact, my other three 110's are still on their original plugs.