If you use a forceful stream of water on a moped, chances are you will get water where it doesn't belong, like inside the airbox, electrical/ignition system, or exhaust.
I use a trickle from the hose and give the whole thing a spot cleaning. On the engine I'll use carb spray on the head where the decompressor valve leaks fuel and collects dirt.
The rest of the bike get cleaned with a sponge, and greasy areas get a shot of AWESOME. This stuff is water soluable and cuts grease.
Since the bike isn't that wet, I'll chamois off the paint and chrome, and let the rest drip dry in the warm California sunhine, or I'll go for a ride.