they are a realy simple carby ,so just buy a new gasket/rebuild kit for it then ,pull it down and clean every single part ,and ide pull the jets out one by one and clean them and then put them back in there correct spot cos some they are different sizes

and it wouldnt hurt to use carby cleaner in when cleaning jets and stuff ,when i did my twins it worked a treat ,gets rid of any carbon and cleans the ally up real nice !

good luck