An improved apparatus and method of having a pair of end caps on a rotor assembly of a multi-pole high-speed generator is provided for use with a turbine engine. The rotor assembly provides improved balancing and/or cooling during generator operation. The rotor assembly includes a plurality of poles and at least one support wedge positioned between each of the poles. The rotor assembly is mounted on a shaft. An annular flange of the end caps restrains the support wedges in the rotor assembly for improved balancing and maintaining concentricity. The end caps may also include a manifold for circulating a cooling medium through the shaft to and from the support wedges to cool the generator.