Anthony ; I have a Ryobi 31 w/C&H ignition on my H-9 Cap. It works ok , I'm not thrilled with the power out put of the Ryobi , but I'm in the process of finding more. I've read some posts where people claim 14lbs of thrust or more, I'm only getting 9 with an 18X8 prop. My plane weighs right at 14lbs without fuel , & still lands well. The thing you have to remember with a cap is to land it a little on the HOT side, they don't glide too well , especially with that kind of wing loading. Hope this helps