The CRF250R shown has an Air/Fuel monitor with sensor mounted to the header near the kickstart. The monitor will register rich or lean conditions instantly on the LED display. The JDJetting kits for the CRF250R were developed by tuning in 1/8-1/4 throttle range increments of the carburetor for best performance. The result is more instant throttle response and improved mid-range torque with the same, great top-end the CRF is known for.