The 10 percent ethanol in our gas is a bugger if the bike sits for extended periods. Some of the suggestions made are OK but my experience has been that you might want to buy a couple new pilot jets and either clean the float needle/seat assemblies using brasso/q-tip or a dremel tool equipped with brash brush and make sure you clean the tip of the needle as well. I generally just replace these things in my business when the carbs have been gummed; you definitely don't want to clean the pilot jets with an abrading wire tool.
