2000 Yamaha YFM400FWA(M) Factory Service workshop Manual, Page 168Get this manual
PRIMARY AND SECONDARY SHEAVES
PRIMARY AND SECONDARY SHEAVES REMOVAL 1.Loosen: Nut (secondary sheave) Nut (primary sheave) NOTE: Use the sheave holder to hold the primary sheaveFirst, loosen the nut (secondary sheave) 2, then loosen the nut (primary sheave) 1Sheave holder: PNYU-01880, 90890-01701