Not sure if relevant but i had an S back about then--traded it on my yz250c & had more fn on that than the C, but anyway, thinking back to replacing rings or piston & rings the thin rings are gap'd to the ring peg 'not stepped over the end of it' or under it. Consequently if you sit the rings in the bore they'll have about 40 thou end gap [or gap equal to the peg size]. Peg comes right to ringland edge pretty much. In other words don't worry if you sit them in the bore & think you have the wrong size. All that's thinking back 40 years [is that right-- hell]. Broke the end off the crank in mid air on full song too [ran outa spark lol], damn near went over the bars when it landed. Re the rings--it's the wear where they scratch past the ports that's the important bit rather than end gap--consequently new rings always sharpens up a two stroke with big holes [ports]. That my opin ion anyway--others might differ.