Does anyone know how to set up the money, bank account, and IRS consequences of organizing a motorcycle rally?

Setting up a motorcycle rally, or any event as a business is pretty much the same as setting up any business.  If you will be accepting money under the business (rally) name, and you are not a corporation, you will need to file a DBA (doing business as).  Once you have that you can open a bank account under the business (rally) name.  As for IRS, that is going to vary depending on your current tax situation, and I would recommend consulting an actual tax person regarding that.