1: Cylinder: 44mm carb manifold intake diameter: 19mm air filter air: 58mm piston 12mm, This kit can NOT work with a 40mm bore engine with a 3/4" wrist. 10mm piston. 2.Quality: 100% brand new. Never used.Professional manufacturing, high quality assurance, high toughness, resistance to wear and tear. corrosion, anti-rust and durable, long time service. 3:Big Bore 53cc 54cc upgrade 2-stroke day 49cc; mini pit ATV Pocket bike Engine cylinder head 4:Fit Model: Replacement for some air-cooled Chinese Mini Moto models, including Mini Dirt bike, CRX50 Dirtbike Coyote Midi Quad ATV Mini Racing bike. Product description Cylinder: 44mm carb intake manifold diameter: 19mm air filter air: 58mm Condition: 100% New. Never used. New & High Quality Color: gold/red as pictures big bore 53cc 54cc engine cylinder piston head; 3 Big bore 53cc 54cc upgrade day of 2 stroke 49cc; mini-pit Bike ATV Pocket bike Engine cylinder head Model: Cagllari CAG Daytona pocket bike CAG pocket bike MAT1, MAT2 pocket bike