2008-2010 Kawasaki KFX450R Factory Service Manual, Page 333Get this manual
BRAKES 12-21 Calipers
Dust Seal and Friction Boot Damage
in accordance with the Replace the dust seals [A] check that the dust sealsPeriodic Maintenance Chart or and friction boots [B] are not cracked, worn swollen, or otherwise damagedIf they show any damage, replace them
Piston and Cylinder Damage