Sport_Pilot,
I checked the valves on both the day I ran them. I was giving them both a final go-over before mounting on their planes. My first post was a cooler and dry day. My second post was a hot rainy day. I am at 605 ft. ASL. I think both are still not broken in good and will get better once I get them in the air for about a gallon. I have ran them enough to get stable needle setting and a reliable, low idle.

I think that .91 four-strokes should be swinging a bigger prop at lower rpm anyway. A four-stroke turning above 10k seems a bit much. A 15x6 gets it in the 8k range which should be more in the power-band on a four-stroke since they make their power more with torque than high rpm. With both engines I cannot tell a difference in the throttle response between the 15x6 and 14x6 so I would say the 15x6 is not too much prop for a .91. What do you guys think? Am I crazy or missing something that is the reason most people use 14x6 on .91 FS?