You also need a special tool to pull the new crank into the case halves but its pretty easy to make one with a piece of pipe and some big washers.
Oh yeah and be careful when you split the cases there is a little steel ball berring that will fall out make sure you dont loose it, it goes between the two clutch rods. but over all its not that difficult of a rebuild just get a clymars shop manual and take your time and follow the instructions step by step
there is also a link to the yamaha mechanics manual on here somewhere its in a pdf format but I think the instructions in the clymars are more detailed
Good luck