The Additional 'O'-ring which we install around the face of the steel end cap is what separates/seals the dirty oil into oil filter cavity.
The outer 'O'-ring still seals the circumference of the clean oil pathway.
Both 'O'-rings are the same original KLR part #671B2555.
Or, I presume, the FREE FRAM 6070 O-ring!
Thanks for the explanation. The extra "quarantining" of unfiltered oil may add thousands of miles of service life before major overhaul.
I have been somewhat conditioned by my Honda experience, wherein NO replaceable oil filters existed on some small engines. Others with the skills, tools, and time might profit from the 100 % filtered flow mod. Respect for the diligence and persistence involved in developing the oil flow mods.