For those that were around for my carb cleaning issues you may well know that I have most likely destroyed my idle jet by trying to shove a filed down nail through it to "clean it out". Anyway while shopping for new keihn #38 jets I saw that there is more than one type of #38. So far I have found series 21 and series 22 #38 jets. Whats the diff? which am i supposed to get?