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Vibration at certain speeds can be caused by bad wheel bearings. Check if the wheel is rotating freely when lifted off the ground. Twist the wheel around the axle, look for any play.
If you need new bearings, we recommend this kit (choose front or rear bearings in "Product Options") :
Kawasaki Ninja 500R 2009, Wheel Bearing Kit by All Balls®. Hands down, the most complete line of wheel bearing and seal kits, All the bearings and seal required to refit a wheel in one convenient package, Premium high-speed bearings feature low drag, double lip seals on both sides to provide...
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