Whilst the cush drive is good unless you start putting out big horse power from a 420 engine you should be fine. The XL rear wheel weighs in at a staggering 12 kilo's , You can always fined a MT 125 rear wheel which has the cush drive. Also if you take some weight out of the engine ( shave the flywheel ) this will help on the gearbox loading. KSI thumbers ran Yamaha YZ or RM wheels with much internal engine lightning. You may also be able to fit one of those new cush drive sprockets.