Mark,
Please heed Rob's advice, it (pressure washing) can lead to huge problems. In fact I would go so far as to advise you to replace all the drivetrain fluids after a +20 mile warm-up ride; Transmission, Swingarm, and Final Drive soon. Don't want to sound like Chicken Little but I've had to rebuild a transmission due to water contamination and it's very costly. Not to mention the possibility of water entering your wheel bearings. And, check the condition of that speedo cable boot regularly. Water, "if' entered to these areas can lead to a slow death of these components.
On the restoring of the plastic; I use a technique I may get laughed at but it works quite well for me. I use silicone grease rubbed into the plastic, then buff with clean cloth. It does little for UV protection but will bring back a nice luster and revitalize discolored and dried-out plastic.
