I use their product (Harley's) called S-100 to wash the bike and the engine.
If you have a plexiglass windshield, you should NEVER use windex on it. Use Harley's plastic windshield cleaner or else it will start to get "foggy' looking and hard to see through. It's called Novus and comes in a blue & white plastic container.
Be careful with the S-100. They recommend that you do not get it on electrical connectors and devices (speedometer, ignition, etc.) Ok on wires though.
It requires no rubbing or applicator. Works on the wheels too. Just spray it on and let it sit a few moments, then rinse thoroughly. The black coating on my engine was really enhanced by it.