Ed,
If you're even thinking about removing the studs for either clean-up or replacement - make absolutely sure we talk first. I've ruined 2 crankcases in my past and both were from failed attempts to remove cyclinder or case half studs. There is a trick to removal and I've followed the advice of my old machinist friend, Mr. Charles. He has removed hundreds of studs from aluminum heads over the years without failure. I on the otherhand ruined 2 cases in just 20 until I followed his method.
First, only remove them if you have to for replacement.
Second, never ever use a tap in the threads - those are supposed to be a tight, taper like fit. A tap in those stud holes is not good.
Third, you "Heat" the assembly in a preheated oven at 250F for exactly 10 minutes - no more, no less. You want to heat the aluminum, not the steel studs. Longer and the studs expand from the heat, less and the aluminum won't heat. 250F.
Fourth, use 2 Visegrips in the 9 and 3 o'clock positions (point is you want them directly opposed) so you can "TWIST" left and not add a side load that only 1 wrench will do. Think of a T wrench - you want 100% energy turning the stud, not loading the side.
I've done everyone of mine this way since and still get a "pucker factor" because these don't give a warning - they SNAP and then you've got a hard piece of steel in a hole surounded by soft aluminum...Not good.
Here is my 836 with the heavy studs installed top and bottom, but as said this is not required. Mine are there because I wasn't sure where I was going to stop with the building of horsepower. Old age caught up and I have more sense today - I don't need to go 130 on a 40 year old bike that doesn't handle or have the brakes for it!!
Best Regards, Gordon