Items Needed:
1. Laundry Sink or Bathtub
2. Gentle Laundry Soap (i.e. Woolite)
3. Towels (2)
Estimates:
Time: 15-30 minutes to wash, 24-72 hours to dry.
Step 1 - Remove the visor

Helm
Step 2 - Place towel in tub
You do not want to scratch your nice helmet, do you? Make sure you put the drain plug in first.

towel in tub