Hello up for sale is a 79 mm big bore kit for the 250/300 already set up rings are installed all you need to do is push piston down connect to rod and then slide cylinder onto base gasket. This is a steel sleeved set up for worry free riding make your 286 a true, 305 with this kit. I have personally ran the set up and one of my swaps for two years now best bang for your buck.