14-19 HONDA Grom: Koso Big Bore With 4 Valve Cylinder Head Kit (170cc) This complete 170cc Big Bore kit with 4V Cylinder Head kit is the perfect add-on for all horsepower enthusiasts looking for performance!Kit includes: 170cc ceramic coated cylinder, forged piston, performance camshaft, bearing, rocker arms, 4 valve cylinde Koso is not responsible for any damages caused to the parts, vehicle, or to yourself and others. Engine parts are not under warranty nor is collateral damage or cost of labor, in cases of malfunction.