Twin Spark +R Superhead 130cc Racing bore kit for the XR100R and CRF100F improves spark efficiency and combustion. Largest valves in class, and the proven forged aluminum roller rockers are included in this top of the line bore kit. 3 SR series cam choices make this kit more versatile than any other on the market. Racing kits include larger finned sleeved cylinder requiring case boring for installation.

• Bore: 58mm  Stroke: 48.5mm
• Kit comes with SR25 camshaft