This is a 2-stroke motorcycle ATV cylinder jug that came in for a bore and hone. It is an aluminum air cooled engine so that is what all the fins around the outside of the cylinder jug is for, to keep it cool. We put the cylinder in our Rottler boring bar so we could bore it for the new and bigger piston. We then mounted the cylinder in our Sunnen CK10 cylinder hone so we could final hone the cylinder to size to give it the proper piston-to-wall clearance for the new piston as well as the proper cross-hatch finish on the cylinder wall for good oil retention. Motor Mission Machine & Radiator 5435 Desert Point Dr. Las Vegas, Nv. 89118 Phone: (702) 649-2366 or (702) 649-0648 Fax: (702) 649-4133 www.MotorMission.com Facebook.com/MotorMission