These are a few of the things that I have found work the best:
Rinse off any loose particles, then walk away. Letting the water soak in lets the dirt let go without marring the plastics.
Wash the moderatly clean ATV plastics and frame with Meguires Car Wash -- Pink Bottle, excellent suds.
Eagle One All wheel cleaner -- Orange bottle, cleans everything from engine sidecases and swingarm, to the chain, and of course the wheels.
I like to use a long soft bristle wheel brush for this.
Dry off everything with an Absorber -- won't scratch plastic like a towel can, and is easy to store for those visits to the Car Wash.
Then go over everything with:
Honda Atv Polish and Cleaner. -- Shines and protects everything. Cleans seats without leaving them too slick. Doesn't attract dirt as bad as others.
Meguires Quick Detailer, -- Loosens anything left over form washing or storage. Doesn't leave the wet look of the Honda Product.
I also like to use these products:
Silkoleene Chain Lube Race Formula -- Dries Clear and won't sling off, only apply to the inside of the chain.
Quick Silver Marine Grease -- Resistant to water and dirt.
Eagle one Wet Look tire Shine -- Looks Great on everything, attracts dirt like mad.
If you must wax an ATV, try Meguire's Quick wax. Spray on, and wipe off.
I also plan on trying Eagle one's Wax as U Dry.
Keep everything you use to clean an ATV as clean as possible. Even the smallest particles of dust in a towel will scratch the plastics when rubbed thoroughly.
These all work very well, and will keep even a black Raptor looking nice. 8)