ORIGINAL: rcpattern
Kevin,
You are right, I love my YS stuff now, but I also realize that for the older more slippery fuses the 1.40RX is hard to beat. It is a bullet proof engine and must less expensive to run. Also, you aren't going to be flying Masters or FAI with it anytime soon. I personally ran the 17X12 with an ES pipe on 15% Cool Power. Very simple setup. Others have played with bigger props and different setups, but I think the 17X12 was easy on the engine and ran fine on 15% Nitro. You are in a position that you just need to fly and that setup will do just that.
Arch
I agree with Archie. This is a very good plane and you are lucky to have found it NIB
I owned one of these but sold it before doing any work on it. However, I set-up two of them for a couple friends. One was flying it with an OS 140 rx and it was OK powerwise (not great, just okay) and the other was flown with a YS 140L which was underpowered. Actually the planes were a bit on the heavy side for those engines pushing 11 lbs with a larger wing than the current trend. The plane was fairly draggy compared to most 6-7 years ago.
Consider using the YS170 cdi in it. That's probably an easier set-up and many guys have experience with it that can help. I am not sure how the soft ally beam engine mount would hold up to a 170 cdi. It's holding up fine for the YS140L for at least 7 seasons on one of my friend's planes