Mujitsu and Tairaku's Shakuhachi BBQ

Ryan Sullivan wrote:

When I am tuning the shakuhachi I craft, there is a consistent issue with Ri.  If I use the standard fingering of 1,2,5 closed, then Ri is too flat to be pulled into tune with a decently sized finger hole: the 4th hole would have to be way too large. However, if I only close 1 and 5,  Ri comes into tune with a 4th hole the same size as the other holes. What are the various factors that would play into this issue?
I am refraining, at first, to post any of my measurements in hopes that it will provide more of an open forum for broad ideas and acoustical theories.
thanks

Ryan,

What if you move hole four slightly higher? If there is equal distance between holes one through four now that could be the issue.
Some hole placement formulas call for equal distance. In this case, moving hole three lower and hole four higher can often
fix most tuning issues.

Ken