This is the B53F jet needle used in the OEM Honda XR650R carburetors.  Genuine Keihin jets provide the best replacement or calibration solution for your Keihin carburetors.  Do not use an imitation, nothing substitutes for OEM quality and Keihin jetting is guaranteed to be the exact size indicated because of high manufacturing tolerances.  The B53F jet needles will fit all Keihin OEM style CVK, FCR-MX, PD, PE, PJ, PWK, and PWM carburetors.  Includes jet needle, jet needle clip, and jet needle set.

The B53F has a thinner diameter at the tip resulting in a richer mixture from 1/8-1/4 throttle opening.