i'm sure my RM250X [i sold as a restoration project a couple of years ago] had a reed inlet like yamaha? if i'm right maybe this is "79 or earlier, somebody will know!! [or was the X 1981 & 1980 the T come to think!!], Always been into Yamahas but damn it i seem to now have 'two' RM250X's [1992], rough as guts but nice to ride--ok sorry, not vintage as such. But---i saw the Oceania vmx at taupo recently listed a pre-90 class so just for argument sake, would a "92 RMX250 be allowed as a follow on model [no change i believe till "93 or later] & started in "89.--food for thought.