Putting this up for a friend.. he bought the bike last a few months back with 23,000ish miles on it. The previous owner had installed all kinds of cheesy chrome covers and other knick knacks. There was a cover on top of the case under the cylinders attached through the top center bolt. The bolt was leaking oil and he wanted to get rid of the cover so he went to harley and got the correct bolt for that location. Long story short, it won't tighten, it just spins. He took the longer bolt that came with the cover since it's a bit longer and put some rubber washers behind it to temporarily fix the issue but that bolt won't really tighten much either.. I was able to find an old post where the guy drilled out the bore all the way through the case and put a nut on a longer bolt. The problem is guys we're warning that that area of the case may have been clearanced for cylinder spigots with his larger bore.. what's my friends best move aside from splitting the cases and are the cvo 110" cases clearanced where that bolt goes through?

 

I would not drill the hole larger but get a longer bolt the same size as the original but long enough to thread through the case so a nut can be used on the opposite side to torque to spec.

EDIT: Axtell and maybe others, includes a thru bolt with their bigger bore cylinder/piston kits. The bolt shaft is machined to a "V" shape so it will not interfere with the larger pistons at the bottom of the stroke. While you don't nee the V shape but do need a thru bolt/nut, you might contact Axtell.

 

I hesitate to offer any advice here! It may be fine to drill the same diameter right through the crankcase, but not a larger diameter. That part of the cases is very thin regardless of the engine spec, so I don't believe being a CVO makes any difference. IMHO it would be worth talking to a local indy for advice. If the thread has been stripped there may not be any space to install a threaded insert of any sort, so it is worth seeking local advice.