Genuine Keihin main 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 99101-357 main jets fit all Keihin CR Special, FCR, FCR-MX, PE, PJ, PWK, and PWM carburetors.  Also fits all Honda XR650R motorcycles.