2000 Yamaha YFM400FWA(M) Factory Service workshop Manual, Page 149Get this manual
CYLINDER AND PISTON PISTON REMOVAL 1.Remove: Piston pin clips Piston pin Piston 3
NOTE: Before removing piston pin, deburr the clip groove and pin hole areaIf the piston pin groove is deburred and the piston pin is still difficult to remove, use the piston pin puller 4Piston pin puller: PNYU-01304, 90890-01304