First my Webra 120s don't like more than 5%. I lean the idle a little more than lean to keep the mid range from loading up. But there are are still throttle settings that will get a little rich. I haven't tried it yet but a couple of good pattern guys that run 2 cycles say to use a uniflow tank on 2 cycles that tend to richen a little in the mid range. I'm going to try one soon.