1.  Nope.  Why buy yourself trouble?  Bargains come and bargains go.  Don't vote with your heart!  Use your head.  The big one!!
2.  Now thats over with . . . is the bike under warranty?  If so, would your seller mind riding over to the local Triumph shop for a look see at its meatballs and sausage area?  At the very least you could learn some good stuff from a Triumph mechanic for free and get a more detailed look at the bike for free, etc.  Milk it, milk it!!
3.  While you're milking it, this might be a way to squeeze a bit of a concession in the price from the seller who probably knows **** well whats wrong with the bike and thats why he's selling it.  Hmmmmmm.  If he thinks he's going to have to go through #2 for every potential buyer that comes along he may accept less just to be rid of the "problem".
4.  Not happy with the deal?  Remember #1.