Yam XT600 Tenere Engine Rattle

[OlyLo]

I'm thinking about possibly buying a '80's Tenere 600 (high 30K miles), although I have been told by the dealer that it has a slight engine rattle.

I havent seen the bike yet, and don't have any experience of the Tenere - can anyone tell me whether this is a common fault or what it is most likely to be and likely costs to repair (if indeed it requires repairing)?

Thanks in advance!
Oly