yes as muskrat said - i have done a few times while head is on the bike (it is better to remove the head though though) - i usually put some heavy grease on the cutting tool to catch any debris. if you get it done at a good shop they can do it quite easily (about 45-$100), typically hooking up a vacuum to the exhaust and having the valve open on the side with the repair to "suckout" any swarth (not sure it works but hey).