The +3mm Big Bore Cylinder Kit (Part Number: 11001-K01) is designed to significantly enhance the performance of Honda CRF250R (2004–2009) and CRF250X (2004–2017) models. With an 81mm bore size, this kit increases the engine displacement to 269cc, delivering a 13.0:1 compression ratio. When used with the Hot Rods #4183 crankshaft, the displacement increases to 277cc. This kit requires case machining, and detailed instructions are included.

Features:

• (+3mm Big Bore Kit) increases displacement to 269cc with a 13.0:1 compression ratio.


• Compatible with Vertex #23535 piston.


• Achieves 277cc when paired with Hot Rods #4183 crankshaft.


• Requires case machining (instructions provided).


• Includes all necessary components for installation.

Package Includes:

• (1) Cylinder


• (1) Piston


• (1) Wrist pin


• (2) Cir-clips


• Gaskets

Replacement Parts:

• Replacement Big Bore Cylinder: Order No. 140408


• Replacement Big Bore Piston Kit: Order No. 131447S


• Replacement Big Bore Piston Rings: Order No. 131447SR


• Replacement Big Bore Gasket Kit: Order No. 263948

Vehicle Compatibility:

• Honda CRF250R: 2004–2009


• Honda CRF250X: 2004–2017

Cross-Reference Part Numbers:

• 422-11001K


• 0931-0118


• 733712


• 2055


• HR11001K01


• 77000-35


• 12100-KRN-672


• 12100-KRN-730


• 12100-KRN-731


• WT400210100009


• P400210100009

Note:

• Case machining is required for installation.