Mandatory Insurance
When you drive in Washington, you must have insurance. But...
Exceptions to mandatory insurance
You don’t need to provide mandatory insurance when you operate a vehicle registered as a:
Motorcycle.
I hope this helps. To be sure, telephone the Washington Secretary of State to inquire: (360) 902-4151 and get information about the Washington Department of Licensing.
I am in Chicago and do not practice law in WA so call those agencies for assistance. Good luck.