The purpose of burnishing is to allow the two surfaces to become accustomed to each other before high RPM and load is applied while mowing, which increases the torque loading of the clutch. This insures better engagement of the clutch mating surfaces and prolongs clutch life.
To burnish a clutch, reduce the engine speed to about half. A typical burnishing time will take anywhere from 5 to 30 cycles depending upon inertia. The burnishing frequency should be done at 2 to 6 cycles per minute. Frequency of cycles and amount of cycles required will depend upon inertia. Typically the larger the inertia, the fewer cycles per minute allowed, and the fewer overall cycles required.