OS 50 SX rpm's:

APC 9x8 @ 16,700; APC 10x6 @ 15,200
Sealevel (Florida)
90 degree Fahrenheit
60% humidity
15% PM, 18% oil contents

The 50 SX doesn't like bigger props. Besides, the rear ball bearings, piston rings and piston sleeve are worn up. Replacement parts exceed the cost of new engine. Had the SX 50 in a quick delta wing. Going for a Dubb Jett or MVVS now.