Naraku 58.5mm Big Bore Kit for 125cc and 150cc GY6 4-stroke engines and engine based vehicles. Easy to install! Just bolt on with no crankcase modifications needed.

• Bore: 58.5mm
• Outer Sleeve Diameter: 60.3mm
• Displacement Increase to 155cc
• Overall Height (cylinder): 91.5mm
• Stud Spacing: 76.5mm