For use on Big Twin 1966-later (except Twin Cam), Sporster 1986-later and Buell 1987-later. Late model aluminum cylinders cannot be accurately honed without using torque plates. Simulates stress conditions when boring or honing. These torque plates are drilled for multiple application use, and can accomodate up to, but not including, a 4 inch bore. To use with Sportster, order four bolts (#97-233) for use with torque plates.