The Taida GY6 Big Valve Head is a great match for the 180cc big bore GY6 engine. It's recommended to upgrade the GY6 cylinder head when doing a big bore cylinder kit upgrade. This Taida Big Valve Head will fit most GY6 with 57mm head bolt spacing. This version of the Taida GY6 Big Valve Head has also been given a port job on the intake and exhaust ports, which increases flow and adds power to an already powerful head!