Not to be argumentative but I worked with Joe on his running quality issue pretty much from the beginning. Each change was made individually by itself to see the results of that change. Improvement was noted, but the last issue to clear up was a mixture change in only 1 or 2 flight attitudes. I had had the exact same experience before on a 50cc plane with a rear carb and as a last resort I put the v-stack on to get the intake air from a less turbulent source inside the engine box, it worked. Joe wanted to try it, appearantly his results were similar to mine. Velocity stacks are not a cure all and seldom do much of anything if the things are running well to start with but there are applications that can create conditions where a velocity stack can have a beneficial effect.

BTW, pretty much all of the 3W singles with rear carbs look like these.