heck, I just use an old kitchen dish brush we had laying around & bucket of soapy water - took off my belt guard a long time ago just so that keeping the belt clean would be easier - when I am done I like to spray the belt down with Lucas Slick mist interior detailer or if I am low on that I use the Lucas slick mist tire spray - - - keeping the belt clean and treated really helps keep things quiet back there
We're supposed to clean the belt? I hose mine off occasionally when/if I wash my Slingshot. I guess I'll need to do a semi-annual wash sometime in the next few months.