The ornamental design for a front side cover for a motorcycle, as shown and described.
FIG. 1 is a front perspective view of a front side cover for a motorcycle showing our new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a right side elevation view thereof; and,
FIG. 6 is a left side elevation view thereof.
The broken lines adjacent the shaded areas represent the bounds of the claimed design while all other broken lines illustrate environmental structure; the broken lines form no part of the claimed design.