2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 137Get this manual
ENGINE REMOVAL c b
INSTALLING THE EXHAUST PIPE AND MUFFLER 1Install: gasket New (to muffler) NOTE: Install the gasket with the chamfer a, located on an inner rim of the gasket, and the chamfer b, located on an outer rim of the gasket, as shown
Installed depth of gasket1.5 mm (0.040.06 in)