Fuel mixture screw: FCR carb. Fits Keihin pumper carburetors (FCR). This part is compatible with all YZ/WR 426F, 250F, 450F bikes, as well as the YFZ quads.It is not compatible with the YZ and WR 400FS. Compatible with all CRF450 and CRF250 Hondas. They are also compatible with the new Kawasaki KX250F and its brother, the Suzuki RMZ 250. Also compatible with 2003 and newer KTM RFS 4-strokes - 450 and 525. It is not compatible with 2002 and older KTM 400 and 520 bikes.