I have converted the new model Ryobi 4cycle AC2 engine- a long learning process. This engine came with a Walbro WYL 9mm venturi carb with fixed jet, relatively small and lean to meet the environmental restrictions. I replaced the carb with a Walbro WYL 10.5 mm Venturi and size .48 jet. Also, removed the magneto and coil and replaced it with CH ignition. To reduce weight replaced the stock muffler. All of these resulted in significant increase in horsepower, I am turning 16X8 masterairscrew @ 7800 RPM.

At this time I am experimenting with a 11.1 mm venturi carb with adjustable high and low needles, optimistic to increase to 2 Hp from present 1.7. Note this engine was producing 1.1 with the stock carb and magneto.

Robert