You can do a lot to make a Ryobi run better.

I just finished one. I put a CH synchro-spark ignition on it. Total overkill, but they gave me a deal on a used ignition system.

Order a new piston ring from Frank Bowman. It's a lot better than the stock ring.

Take the cylinder off the case and dremel the intake ports a little just to smooth them up. Don't remove alot of material. You just want to smooth the radius' a little to help with fuel transfer.

On the backplate; bend the reed valve stop out as much as you can get it without letting it hit the crank. This will let a lot more gas in.

Get a bigger carb. I've got a McCulloch chainsaw carb on mine. It's a Walbro WT348. It's a perfect fit. Bolts right up. And it's a lot bigger than the stock carb without being TOO big.

Lighten it up. Machine off the mounting lugs where the coil used to bolt up. There are 3 other bolt boss' on the front of the engine. Cut 'em off.

If your still in doubt about the performance on the Ryobi--check my add in the Giant engines forum. I've got a nice Craftsman 38cc conversion engine for sale. It's got a Frank Bowman ring and an electronic ignition.