Accelerator Pump Rebuild KitsPoor performance & bogging on acceleration are signs that you may need to rebuild the accelerator pump.All of the necessary parts to rebuild the accelerator pump circuit are included. Kits for vehicles with multiple carburetors include all components for all carburetors. Fits: Yamaha WR400F 1998-2000 WR426F 2001-2002 YZ400F 1998-1999 YZ426F 2000-2002