You should start with one at a time that way you don't mix the parts up between carbs. Plus if you forget where something goes you will have a duplicate carb for reference. Clean out all the jets, the mains, and the pilots, and make sure they are not plugged up. Clean the slides, as well as the floats and bowls. I usually take compressed air and blow all of the tubes that are drilled through the carbs just in case there is any dirt or sand in them. Plus when you put them back on the bike make sure you put the crossover tube back on, and then sync them together with a carb sync tool............ :thumbsup: