MCB Stage-1 Top-End Rebuild Kit with cylinder for 1999-2022 Yamaha YZ250 . This engine rebuild kit includes a Wossner Premium Forged Piston /Pin 8216DA, Genuine Riken rings, clips and Top-End Gasket Kit and a . Everything you need to service your MX Top-End. This listing includes an OEM original Yamaha YZ250 cylinder, not a Chinese aftermarket cylinder with extremely poor port shapes, jagged chamfer ports etc. These Chinese cylinders are down on power as compared to OEM cylinders. This listing does require you to ship your old cylinder core to us prior to shipping the entire kit. Once ordered we pull it, hold it and ship it typically the same day your core arrives. If you are in a timing issue, we can charge you a core fee and ship the kit. Then you have 15 days to get us your core back and then we refund the core fee back to you. Cylinder Casting Numbers 5UP-11311-21-00, 5MW-11311-02-00, 5CU-11311-00-00 You may optionally choose a Pro-X (CAST) piston below. 01.2321.A MAKE SURE YOUR CYLINDER IS NOT AN AFTERMARKET CYLINDER, PORTED OR IRON SLEEVED (IF YOUR CYLINDER FALLS INTO ANY OF THESE CATEGORIES WE WILL NOT BE ABLE TO PROCESS YOUR ORDER.