Planes, I have only been successful modifying one carb, the one on my Webra .91. I carefully slanted the end of the spray bar, maybe 10 degrees, and either I lucked out or just did the right thing but it cleaned up the midrange. I slanted it in towards the bottom of the carb, all other carbs I've fooled with got worse. By the way the Irvine Jet Stream carb for the Irvine .72 fits the Webra .91 and 120 perfectly, same venturi dia. and neck dia. Irvines are the best carbs in our hobby.