Route 66

there's a few companies that you can use but Eagle rider is the best known company,they do a guided tour or you can go it alone and just hire a bike for about £80-£100 a day..fuel and accommodation are cheap. or if you prefer the likes of eagle rider will supply you with a bike and organize all the accommodation for you,be warned though there is a lot of nothingness on route 66 and straight roads, the best part is the last 600 or so miles over on the west (i did that as part of a bigger tour about 10 years ago) the company i booked with were H-C Travel in the UK, If you have a look at these web sites it will give an idea of costs (you will have flights to add on)
http://www.eaglerider.com/guided-motorcycle-tours/route-66-motorcycle-tour

http://www.thelostadventure.com/project/self-guided-motorcycle-tours-route-66

https://www.orange-and-black.co.uk/self-guided-tours/route-66-original/

 

Worth looking at Henry Cole's "Worlds greatest motorcycle rides" on youtube - he's done Route 66 - apparently a lot of it is missing!