Dr. Pulley BMW 600 & 650 HiT Clutch Dr. Pulley HiT Clutch 302002 with 55 degree pillow springs for the BMW C600 Sport and C650GT. The Dr. Pulley HiT Clutch has 2 sets of springs at work: the clutch spring inside controls the movement of the clutch pads towards the clutch bell through centrifugal power. The second set of torque springs (pillow springs), externally mounted, controls the pressure by using a push pin on the clutch linings against the clutch bell. This prevents most of the slipping phase of the clutch, thus creating le ss friction and allowing less heat to be created. Heat is lost power! Thus your scooter will accelerate much faster due to the power transfer occurring at a lower RPM. The clutch can be customized to all personal needs. For example, if you want to get more power at start, choose a stronger clutch spring to increase the starting RPM. If you want to shorten the slipping phase of the clutch, you should use a weaker torque (pillow) spring. For an extreme start, choose a strong clutch spring and a ve ry weak (or no) pillow spring. Click Here to view the full Dr. Pulley HiT Clutch PDF. Overall Outer Diameter: 174mm Center Opening: 44.5mm (width), 48mm (height) 55 Degree Pillow Springs Includes an Assortment of Pillow Springs and Clutch Springs for Fine Tuning Reduces Clutch Slippage Improved Clutch efficiency