You shouldn't have any problem fixing that broken stud on the right fork.
After removing the other 3 nuts, you should be able to remove the broken stud with pair of pliers, or vice grips. Perhaps you will need to tap the broken stud with a hammer, or heat it with a torch, but it should come out fairly easily. Some penetrating oil will also help loosen the broken stud.
If you can't find a replacement for the stud, just substitute a metric bolt with the proper length. The stud is size M6x25, and costs $0.56 in the United States; it's part #33 in the following diagram.
If you need to substitute a bolt for the stud, the bolt will need to be shorter, perhaps M6x20 or M6x15. You can replace the bolt with the proper stud when the opportunity presents itself later.
2005 XR650L: Shorai Battery Relocation, Spud Oil Cooler, XR650R C/S Sprocket, Reinforced Subframe, Chain Slipper Roller, Performance Design Lowering Link, Baja Designs Headlight, FMF Hi-Flo Header, ManRacks SD Rack, ManRacks Front Fender Farkle, CST Surge I Front Tire, D952 Rear Tire, Tusk D-Flex Handguards, Uni Air Filter, No-Toil Evolution air filter oil
Spud Rider screwed with this post 01-16-2013 at 07:18 PM