2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 185Get this manual
CLUTCH EBS00297
REMOVING THE CLUTCH 1Remove: clutch cover NOTE: Loosen each bolt 14 of turn at time, in stages and in crisscross patternAfter all of the bolts are fully loosened, remove them2Straighten the lock washer tab3Loosen: clutch boss nut NOTE: While holding the clutch boss with the universal clutch holder 3, loosen the clutch boss nut_
Universal clutch holder PNYM-91042, 90890-04086