They probably only need to be cleaned well, removed the floats and needle and seats. Remove and clean the all the passeges and the main and pilot jet. Its not a real hard job to do. But unless you have a manual and are somewhat familiar with it, I dont think I would recommend it. You could take them off and take them to a shop and let them do it. I would guess 1 1/2 to 2 hours labor at the very most...