Ya'll aren't gonna believe this
I just brought down my ultimate with a os 120 mark III and after 6 years of sitting and with no after run oil

I took out the plug and valve cover and sprayed wd-40 in cylinder and down valve push-rod guides and fueled it up turned it over for 30 seconds,,, put plug back in and it started on the first compression[X(]
I opened both needles 1/4 turn and then just tweeked them a bit and the motor runs PURRRFECT
I have a 3 position idle switch and the highspeed idle sounds good as well as the landing idle and the kill position still works[X(]
I'll say this much
The OS 120's sure seem reliable[8D]