If you are taking the carbs off you may as well open them up to inspect the jets . The pilot jet is the small one and it can get blocked very easily .
Let us know how you are getting on .
EDIT - it allmost sounds like you are loosening the inlet manifolds , look at the carbs where they slip into the rubber , you should see a black steel clamp , look for the star screw to loosen it . It is normally at a angle so that you can get access to it from under the frame spar