Before you get into fuelling, first thing I'd investigate is the idle speed on a warm engine. As a new bike runs in the idle settles and is not necessarily the same as what was set when it was given its PDI.

All XTs are prone to the problem you have if the idle speed is too low. It needs to be 1400-1500rpm otherwise it will stall coming off the throttle and back on again. Often they can be as low as 1200rpm, which is no good. The reason it isn't a problem starting from cold is the fast idle mechanism raises the idle, effectively hiding the problem.

__________________