ORIGINAL: tele1974
From what I have read the OS 120AX is stronger motor than the Saito 125. My Saito is spinning the 15 x 8 at 8950. So more prop? I would have gone lower in pitch to keep the RPMs up. I must have it backwards.
You should be able to run a 16X6 at the same RPM. According to Saito, anything from 15X7-17X6 should be fine. If you fly off of grass a 17 inch may cut the lawn.
Ihave about 5 different props Iexperiemented with, recommended by OS and what a majority of people here said, and put on six flights with each prop. If you searched this thread you will find some positive comments with a Saito 125 running a 16X6.
http://search.rcuniverse.com/search....5&start=30