Hi guys, i bought a set of CB500/4 carbs from a guy that had not had them on a bike for ten years and they were pretty dirty on the outside but they were cheap so i took the chance i could use them for my sons bike. Upon taking off the float bowl i was suprised how clean they were, so i removed the slow jet and tried to blow through it but nothing and that happened on all four. So i was a bit confused because i thought you should be able to blow through them but because all four were the same and they were very clean inside i started to doubt myself. What do you think? Thanks Don.