It's pretty common for the carbs to re-plug up after cleaning a nasty set out. Try as you might, you never seem to get every last little bit of gunk out. Filling the carbs with gas and putting them in service seems to finish the job for you, lol. So far, I've had my '83 carbs partially plug the right pilot jet twice and the left choke jet once. Luckily I was able to "fix" the issues by just dropping the bowls, carbs still installed, and removing the pilot jet. Inspecting it closely, I could see gunk in it partially blocking the orifice.