Hi Speed Honda CT125 (Trail125) (JA55) and other older horizontal engine 57mm bore up & big valve cylinder head kit (148cc)

This is a big valve cylinder head for Honda's old horizontal engines. The intake is 28Φ and the exhaust is 24Φ. Please note that this product cannot be installed on a stock cylinder. It is compatible with cylinder bores of 56Φ or more.
By using big valves, the efficiency of intake and exhaust is dramatically improved. Furthermore, the ports have also been enlarged, resulting in a more satisfying engine feel.
A high-lift camshaft and reinforced valve springs are included as a set.

This is a big bore kit for Honda's old horizontal engines. While other companies offer larger displacements, we concluded that a 57mm cylinder bore offers the best balance in terms of engine durability and high-rpm extension. We have tested this product for over 10,000km under harsh conditions with no problems. We are confident that this is an excellent product.
*When installing this product for public road use, you will need to apply for changes to your license, insurance, taxes, etc. Please handle these matters yourself.