DirtBike 125cc Cylinder Head & Valves, fits most Apollo Dirt Bikes with the 125cc Honda Type horizontal cylinder engine with the 52mm Bore. NOTE: Please be sure your model has a 52mm bore prior to ordering. Some units may have a different size.Our head comes with a 28 tooth cam sprocket. Some models may have a 32 tooth cam sprocket. This head will not work if you have a 32 tooth sprocket.