I claim the ornamental design for an axle slider block for a motorcycle, as shown and described.
FIG. 1 is a front elevational view of an axle slider block for a motorcycle;
FIG. 2 is a side elevational view thereof;
FIG. 3 is an end elevational view thereof;
FIG. 4 is the opposite end elevational view thereof; and,
FIG. 5 is a perspective view thereof on a reduced scale and shown in position of use.
The broken line showing of the environment forms no part of the claimed design. The broken lines immediately adjacent the shaded areas define the boundaries of the claimed design and form no part thereof.