I was adjusting the air/fuel screw and I can turn it all the way in to seat without the motor starting to stumble. Is this a sign of an intake leak or is it possible for little change when needle is seated.

 

if you can turn it all the way in with out your bike stumbling or dying there is a problem. It could be that your slow jet is way too big. It could be that the screw was seated to hard damaging the seat causing an air leak. My bike will not run if it is all the way seated nor would any of the ones I have worked on.