Cylinder Works Standard Bore Cylinder Kit. This cylinder looks virtually identical to the O.E.M. and is nickel silicon carbide coated for long life. Super convenient - just purchase and install. Virtually identical in appearance to stock. Nickel silicon carbide-plated for long life. Honed to exact size for easy piston installation. All kits come complete with gaskets, cylinder, Vertex piston, rings, pin and clips. Detailed Specifications: Compression ratio (x:y): 13.5:1. Cylinder diameter (mm): 77.00. Displacement (cc): 249.00. Piston diameter (mm): N/A. Note: Uses Vertex #23861.