Tim, it looks great. I have been doing conversions on the Briggs and Stratton four strokes, I want to do a Honda next. We put a Birrelli carb on one of our Briggs last night, its way to much carb for the engine but it did run decent, we need to downsize the carb to make it easier to adjust. I had also planned on putting a four stroke on my Sopwith Pup but didnt want the large jug sticking out the bottom of the cowl, so I went with a 25cc featherlite instead. Here is a video of my Fokker DVII with the Briggs and Stratton four stroke. Its turning an 18-8 at 6500rpm, stock carb. A friend mounted his Honda on a 1/4 scale Fokker DR1, it looks good inverted on that plane. Is the WYK61 the same configuration as the 38 just with a high end needle? Mounting wise.

http://media.putfile.com/Fokker-DVII-Sunny-Day

http://media.putfile.com/Sopwith-Pup