I bought an easy out small enough for that at OSH for 4 bucks. An alternative that might work is to cut a slot in it with a dremel cut off bit and use a small flat head screw driver. The only problem with that is when you cut the slot you will end up cutting some of the engine case also depending on how tight the stud is in there you might not be able to get enough torque on the stud to get it out that way.