2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 182Get this manual
A.CMAGNETO ENG
4Tighten: A.Cmagneto rotor nut 1
65 Nm (6.5 kg, 47 ft lb)
NOTE: While holding the A.Cmagneto rotor with the sheave holder 3, tighten the A.Cmagneto rotor nut Do not allow the sheave holder to touch the projection on the rotor_
Sheave holder PNYS-01880-A, 90890-01701