I claim the ornamental design for an axle slider for a motorcycle, as shown and described.
FIG. 1 is a perspective view of an axle slider for a motorcycle;
FIG. 2 is an enlarged elevational view at an angle thereof; and,
FIG. 3 is a enlarged front elevational view thereof.
The broken line showing of the environment is for illustration purposes only and forms no part of the claimed design. The broken lines which define the boundaries of the claimed design form no part thereof.