There are 2 styles of countershaft sprockets used on Ducatis. On the left is the style A used through 2002, with threads for the outer fixing plate. Style B of countershaft sprocket (right) doesn’t have threads for a retaining clip because it uses a large nut to retain the sprocket. The Style B sprocket is also .5mm thicker from front to back (offset).
Look at your countershaft prior to ordering
NOTE 1: 800cc and the MS4 motors sometimes have a different offset to the sprockets. In this case, mount the sprocket with the flat side towards the motor. If that doesn’t work, you’re outta luck.
NOTE 2: Dropping a tooth in the front sprocket yields the same approximate results as increasing the size of the rear sprocket 3 teeth.
NOTE 3: It is recommended that the chain be replaced when replacing the sprockets. Worn sprockets accelerate chain wear by stretching the links in a chain. You can get your chain here.