"he wants the bike before I cash the check" . . . . ?
Selling over the internet is done by in a "caveat emptor" manner - buyer beware - not seller beware!! He must meet you terms not the other way around.
If this person is truly a quality buyer, BMW enthusiast an over all good motorcycle rider he will take the risk not you.
From what you have said appears to a be a SCAM to me . . . wants to buy the bike unseen, does not meet you, and has the bike shipped while you have no security . . . right!!
Sit back, relax and make him go through all the effort - you are not a dealer and many of the issues that will come up will be foreign to you, be cooperative but remember you are looking for a buyer not a shopper that shows up with a desire, skills and abilities to make the sale happen.
I have sold two bikes in recent years ('02 K1200LT and '07' R1200GS) and in each case I had funds in place, secured by my financial institution that could not be withdrawn or cancelled. I also bought a '09K1200LT in November of last year from a member here and I went overboard in completing the transaction and making and getting the seller comfortable in the transaction - I paid off his loan, held the title and send him a certified check the picked up the bike!!
Good luck . . .