2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 28Get this manual
ENGINE SPECIFICATIONS Item Valve, valve seat, valve guide Valve clearance (cold) IN EX Valve dimensions Standard 0.100.15 mm (0.00390.0059 in) 0.200.25 mm (0.00790.0098 in)
Head Diameter Face Width
Seat Width Margin Thickness
"A" head diameter "B" face width "C" seat width
IN EX IN EX IN EX
26.927.1 mm (1.05911.0669 in) 27.928.1 mm (1.09841.1063 in) 2.26 mm (0.0890 in) 2.26 mm (0.0890 in) 0.91.1 mm (0.03540.0433 in) 0.91.1 mm (0.03540.0433 in) 1.0 mm (0.0394 in) 1.0 mm (0.0394 in) 4.4754.490 mm (0.17620.1768 in) 4.9654.980 mm (0.19550.1961 in) 4.5004.512 mm (0.17720.1776 in) 5.0005.012 mm (0.19690.1973 in) 0.0100.037 mm (0.00040.0015 in) 0.0200.047 mm (0.00080.0019 in)