2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 230Get this manual
CARBURETOR
ADJUSTING THE ACCELERATOR PUMP TIMING 1Adjust: accelerator pump timing
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
NOTE: Insert rod with an outer diameter equal to the specified throttle valve height under the throttle valve plate to achieve the specified value
Throttle valve height 3.40 mm (0.134 in)