Banging in the exhaust... I wonder if the pilot air screw is too far open.
Simon, banging mostly means to much air is allowed to pass by due to a worn slide, or a air leak somewhere...
Sometimes also in combination with a retarded ignition.
1. Check your exhaust pipe, especially the conection on the head stub.
2. Are you realy sure there is no air leak between the slide and the body...
3, Two turns out should be a very good starting point for the pilot air screw.
4. Does the banging increasing or decreasing when you alter the pilot air screw?