I purchased this Big-Twin timing cover un-drilled.
Sportsters utilize vertical mounting holes, where as
Big Twins use horizontal.
Rather than drilling through the polished cast
I decided to make an adapter plate that would
utilize the original horizontal mounting locations.
Here it is drilled and counter bored
Installed to check fitment. I counter bored the
holes further to ensure the new cover would
fit flat. Next (sorry, forgot to take a pic)I marked
drilled and tapped the horizontal mounting
locations for the new cover.
Now on to the new cover. I drilled the mounting
holes and using different shaped stones I clearanced
them to accept cap head screws.