Flying Horse 2-Stroke Motorized Bicycle Engine Clutch Wheel Nut &ndash; Gas Bike Clutch Flower Nut The Clutch Wheel Nut fastens to the clutch pin mandrel through the large bevel wheel on any 2-stroke 48cc or 66/80cc motorized bike engine To install, simply unfasten the old clutch wheel nut from the clutch plate and mandrel by disengaging the motor. Install the new nut on to the pin and plate and you're ready to ride