Clutch kits available for stock or oversized tires. These only fit models that have the newer torsion spring secondary clutch. To improve low-end performance and for sport-oriented applications. Also enhance response and backshifting on soft and slippery terrain, as well as the adjustability to tune for a specific application and further modify the adjustment if other conditions require it. For changes of tire size or specification which may require adjustments to the transmission, the following two kits are suggested. An instruction manual is included which contains information on how to convert the transmission. The new flyweight set designed for this application can be used for both kits. 472-DBC80013 Specific for all units fitted with 26 to 27-in tires (including stock) and use the stock secondary spring. Detailed instructions provided for conversion procedures for different tire types and specifications. Stock secondary spring best suited for this application. 472-DBC80013M For 28-in or larger-sized tires used primarily in sand dune application (any tires) and also includes a different secondary spring. Set Up instructions guide also describes the setting for 27-in wheels or smaller in case one decides to put back stock tires. This kit is for 28-in and larger tires, primary sand dune applications (any tires), and also includes its own secondary spring.