I had a similar noise last year. I checked and checked my valves but it never went away. Mine was a cracke piston that finally went boom.
I would start with the valves, if that doesn't do it then I would go deeper. The Red Line assembly lube worked really well for me.
thanks for the suggestions guys. 
never really messed with the bottom end of a 22r so could be a learning experience.
It is a good learning experience, I'm glad I did it.
