The ornamental design for a frictionring for a motorcycle brake disc, as shown and described.
FIG. 1 is a perspective view showing the front, top and left side of a friction ring for a motorcycle brake disc which forms my new design;
FIG. 2 is a perspective view showing the rear, top and right side thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a right side elevational view thereof;
FIG. 7 is a rear elevational view thereof;
FIG. 8 is a bottom plan view thereof; and,
FIG. 9 is a front elevational view thereof, with an environmental brake disc attached.
The broken line showing of the motorcycle brake disc is provided for the purpose of illustrating environmental structure and forms no part of the claimed design.