Simple Green - Normal Garden Hose - Toilet Brush. After you get the majority of the crap off (which this will do in about 5 minutes tops), you can detail it as finely as you'd like using any of the other products listed in the thread here.
Just used some on my helmet this morning, it's made by a company in Marietta, GA and still works just as well as it did with the Honda name on it.
there should be a product called "MONGO" dude, this bolt's stuck. here, try some Mongo! damn, that's things dirty. here, try some Mongo! what? this is fucking stupid. here, try some Mongo!