Its a YS63 pre-S version.
I run my engine dry each time.
I fly just about every week or every other week. It rarely sits for a month.

Actually very little rust for 6 years and 40 gallons...but I saw a tiny bit and I want to get a handle on it before it gets to be a real problem. This is not a new motor and has seen alot of run time. I think the origin is in the value train...only affected a few parts...99% of them were fine. I think it was only on the little nuts. The bearings feel fine still and the motor is "smooth"..no grit. However, when I tear it down, I'll know....its the only way to be sure.