2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 192Get this manual
BALANCER
INSTALLING THE BALANCER DRIVE GEAR AND BALANCER DRIVEN GEAR 1Install: balancer driven gear NOTE: Install the balancer driven gear onto the balancer while aligning the punch mark on the balancer driven gear with the shorter spline on the balancer end2Install: balancer drive gear NOTE: Align the punch mark on the balancer drive gear with the punch mark on the balancer driven gear Align the punch mark on the balancer drive gear with the shorter spline on the crankshaft3Install: lock washer New balancer driven gear nut 2