Scota, The Lehr trimmer I converted was too weak with propane to swing a useful prop, but it makes good power with gasoline. I used a Walbro WYK-194 carb, the same as the one I bought for the Honda GX35 conversion. It turned 6400 RPM with a 18x6 prop on gasoline and magneto. Not bad for 25cc! The Lehr is a Chinese clone of the Subaru Robin EH025 engine. Here is a shot of it making wind;