The ornamental design for a storagebox for two-wheeled motor vehicle, as shown and described.
FIG. 1 is a perspective view from above of a storage box for two-wheeled motor vehicle, showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a right side view thereof; and,
FIG. 8 is a top plan view thereof shown in a position of use, with the broken lines illustrating environmental structure that forms no part of the claimed design.