classic motorcycle forum

hello lads, this is my first attempt at this site... looks very interesting. i am restoring a '36 mod 9, '31 mod 9, and soon starting on a '35 mod 9. i know enough about 'beams to be dangerous, but  i wish to know if anyone knows why in the rockerbox of the mod 9 there is a 3/8" spring and at the end a ball bearing the front is situated with a slotted adjusting screw with an orfice. we know that the small #55 jet floods the gallery with oil that gravitates to the guides, the exess returns down via the tubes onto the cam gear. so why the ballcheck?? there's no pressure?? also, if one fits a Mikuni to a mod 9, it will preform like a stratovarius!.
leon