Do notfollow this advice unless you know exactly what you are doing. Most of the time people make their problems worse by changing the lever height. Trying to get rid of every last bit of midrange burble is futile and unproductive. Some midrange burble is normal and natural for these lightly loaded engines, raising the lever height will only increase it,instead of decreasingit. If it's gone by 1/3 throttle and you have the adjusted so it's as lean as possible and still have a good transition when warmed up, it's good to go.