Loncins have the Honda CRF stud spacing ... Lifans and other BVH engines have wider stud spacings ...
Dabombs suggestion is about all you can do ... It would help if you heated the alloy boss around the base of the stud with a butane torch while keeping the heat away from the stud itself ... That way the alloy will expand and release its grip on the stud thread , allowing it to be screwed out easier ... Sometimes they can be in so tight that they snap off ... that's when the fun and games begin ...