Steering Stem
I have the tool at home. I'll see if I can get the size for you. There's a post where I asked the same Q recently. If you get the search to work, find it under one of my posts.
it's not just that bolt. once you remove it you'll see that there's another bolt that you need a "special" tool to remove or turn. i think a spanner wrench should work on that though. as far as the klunking, it may be time to change the head bearings.


