does it only do it when slowing down or even if you hit the throttle will it do it standing still. I know I had a friend who had a problem like that and his sprag bearing or one way bearing behind his clutch went out. On his bike if you hit the throttle hard and on the idle down turn it off and you will here it winding down. this is all done out of gear. just might want to give it a try. good luch