First thing is, you´ll have to break down, and have the carbs rebuilt. If that fool did what you said he did, there no way of knowing what else he did. Its not cheap, you´ll probably end up spending like 600 bucks to rebuild them. or just get some 29mm Flatslide Carbs. The bike will fly and still get 40 miles per gallon. if your getting 18 mpg, that thing is spitting raw gas out your pipes. good luck.