Hucklekatt, i am fully aware of the fact that 32mm carbs were used in the newer models but really what does that have to do with my problems with the 28 mm carbs that are on my bike? to restate I have a 1999 royal star standard or xvz1300a or royal star boulevard ( no it's not a suzuki) with 4 28mm mikuni carbs and am getting really poor mpgs. It is firing on all 4 cylinders. I have a modified air box, jardine slash cut 4into 4 exhaust and a barons jet kit installed. you are absolutely correct I am not mechanicly(can't spell either) inclined which is why someone else installed the jet kit. My question is this; with the mods that have been done what jets should be in the carbs? and what if anything would you do to improve mpgs? thanks, Chris