Detergents with special wetting agents will help. The wetting agents reduce the surface tension that produces those beads of water that dry and become water spots. When you rinse, don't use a spray nozzle, just flood water across the surface in a solid stream to help promote the sheeting action.
Doing a final rinse with deionized water, which is what the car washes use for the so-called "Spot Free Rinse", and then blowing the bike dry to eliminate the drips and blow back from hidden and trapped water on the first ride, will produce a much better result. Be prepared to still do a little touchup with a microfiber towel and detail spray, since there are no 100% methods I've seen yet.
The Mr. Clean filter does produce a small volume of deionized water, and I do use one since I'm too cheap to spring for the big bucks to buy and install a commercial grade system. The filters don't last very long and tend to be very expensive for what you get, and I wouldn't have bothered with it if my wife hadn't bought it for me as a present. In other words, it's better than nothing but don't expect miracles.
Jerry