I sent your question to US National Certified Tech Inspector John Motley.
Here is his reply to me:
125 MAX: Cylinder with pneumatic timed exhaust valve. Cylinder has to be marked either identification code 223 997, 223 996 or 223 993.
– See more at: http://www.gorotax.com/rules-and-regulations.html#sthash.lMEdOgie.dpuf
PS. My Cylinder is 223 997
That cylinder is eligible for all series that run 2014 USRMC Rules including the Nationals.
