I just use automotive wash soap and the sponge/mitt thingy like for the car, plus a plastic bristle veggie brush for around the cooling fins on the cylinder and rim/spokes and such. Hose down with the finest mist setting on the garden sprayer thing. Dry with thin cotton dish towel, although I'm sure there's better stuff for that. Only thing I didn't get wet was the bar bag and saddlebags, took them off.
Not real fancy, but gets the bugs off!