Did you change the lifters? are you sure one isn't in backwards? Oil hole on the lifters should face the engine case.

 

I pulled the offending lifter yesterday, cleaned all the oil out with parts cleaner, pumped a lot of compressed air through it, re primed with oil, pumped more parts cleaner and air through it, re primed and reinstalled.

It all seems to be behaving as it should now. think it was just getting stuck somehow. Go figure...

on a different note, here's why you shouldn't use Chevy V8 lifters in a V Twin..

 

Glad you're sorted out! That's an excellent video, S&S are an impressive company. That test bench situation is a really nice setup. S&S Premium lifters are in my motor now...

 

S&S Certainly have their **** together. Running a set of their 583 cams ezy start , real nice.