BEFORE YOU ORDER — MEASURE YOUR JET FIRST
Remove the jet from your carb and physically measure it. If it does not dimensionally match this listing, this is not the correct jet — do not buy it.
Buyer is solely responsible for confirming the correct jet size before purchasing. Do not rely on year/make/model fitment guides — they cannot be guaranteed 100% accurate.
All jet sales are final. No returns or exchanges — no exceptions.
Genuine Keihin 99101-357 series hex-head main jet for Keihin performance and OEM carburetors. This family is also commonly cross-referenced as KH25 and is sold as size-specific jets in the 99101-357-XXX format, with the final digits identifying the fuel-metering size.
The 99101-357 is the common large-body Keihin hex main jet used across high-flow carburetor families including FCR, FCR-MX, PWK, PWM, PJ, PE, and CR Special. The original listing also called out Suzuki RM-Z250 use and listed CR Special, all FCR, FCR-MX, PE, PJ, PWK, and PWM applications.
Dimensions: 16.5 mm overall length with a 6.0 mm hex head and M5 x 0.8 / 4.9 mm thread. Common stocked sizes on this product run from 080 to 230.
Use the stamped size to match the existing carburetor setup or to rejet in controlled steps after engine, exhaust, intake, altitude, or fuel changes. Jetting should be confirmed on the motorcycle or engine being tuned rather than assumed from model-family fitment alone.