I forgot about the part where you take your little bike to the hardware store and it melts the top end on the way back and you have to push it home. And also the part about how cylinders for it are unobtanium.
1985 Yamaha Riva 125 XC125N if you have any leads on top end parts. Yes, I already saw the $425 new old stock one on eBay. No the later model cylinders will not work.