Clutch plate replacement is an often overlooked service on ATCs.
Consider that and ATC has at least twice as much strain on the drive train due to additional traction and you will realise that the clutch plates are subject to accelerated wear.
Consider replacing your plates with these quality Japanese replacements.
Suits ATC250ES 85-87, ATC250SX 85-87, TRX250 85-87. 5 disc set
