Charging Flywheels are a mainstay of the performance market, pioneered, patented, and made famous by Jetinetics. These are the world's finest, billet CNC machined, balanced, and best engineered flywheels in the world, period. Used by top pro riders in closed course and surf, these are lighter, stronger, and add incredible throttle response to any engine combo. Bolt-on easy and highly reliable, experience why these are the choice of champions worldwide. The 0323 fits all Sea Doo 580/650/720 engines with no modifications needed. Timing is factory spec and these flywheels are supremely lighter than their stock counterparts. Because the factory original Sea Doo flywheels weigh in at a hefty 7.5 lbs, the Jetinetics flywheel is a staggering 50% reduction in weight coming in at about 3.75 pounds. This huge reduction in rotating mass will not only make a huge difference in performance and throttle response but will also significantly reduce the bearing wear on the crankshaft and engine stress resulting in longer engine life as well as shocking performance gains.