RE: prop size?
I just finished converting and bench running my Echo 23.6. Used a Master Airscrew K series 18/6 and turn just over 8200 with it a tad rich. Will be replacing the OS 91 4-stroke in my Balsa USA Eindecker with it. May try a 17/ 6 or 8 later on. SHould be real nice to run when I am done.