Hi I'm breaking in a 120 SP and have some questions. I've run four 14 oz tanks of 10% Omega fuel through the engine in 15 minute intervals. I ran it mostly around 2500 RPM. Now I'm trying to tune the engine to run right and ran into some trouble. The engine will die below 1900RPM without the glow driver. It transitions quickly and smoothly to full throttle, about 5000RPM, but then bogs down to 4800RPM. I turned in the High Speed needle in increments until it is only 3/4 of a turn before it bottoms out. I also turned in the low speed needle 1 full turn in 1/4 turns. I'm using an APC 15.75 x 13 3 blade prop.

I've never heard an RCV engine before, so I don't know how it is supposed to sound, but it doesn't sound smooth to me. It seems to change between two sounds, a whirring sound, and then it goes to a deeper tone, like a governer bouncing back and forth on a lawn mower.