fdjizm if your new to tuning the carbs have a good read on the tuning on massive mods wen site this should give you a good base idea as these carbs are slightly differant to tune

the novarossi carbs do fit in i have a couple of os speed carbs that i have been using and trying differant things with

the gx series carbs are a whole lot better then the older ones but the high speed needle is a very fine tune when adjusting it no more then 1/2 at a time