Motorcycle Repair: CB700SC Engine Noise - Known Problem?, rod bearing, volunteer basis

Question
I have been looking to purchase a 1984 CB700SC that an acquaintance has for sale.  The bike is complete and is a good price, but he says the engine started to make noise all of a sudden.  It was a knocking sound and apparently was obvious and loud.  He says it was in Cylinder number 2 and that after talking to a mechanic he was advised not to run it any more.  According to this mechanic, the 700 engine had some "Known" problem with Cylinder 2 and that it was likely the cause of the noise.  I feel comfortable in repairing whatever may be the problem, but do you know of any known problems with these engines?  The last thing I want is to tackle an expensive fix, but if it might be something simple ?  Let me know.  

Answer
i have definitely ran across a few with similiar problems one was a wrist pin on the piston the other waas a rod bearing but all i all they are very good engines ,people dont understand they are man made and we do make erros sometimes but that doesnt tell me thta these engines are not dependable they are very good engines purchase it but wrk him down on the price . there is also a site called  oldmanhonda.com its an awsome site for vintage hondas loads of downloads ,manuals etc. i hope this answer has helped you. p.s please leave feedback for me we do this on a volunteer basis ,you may also nominate if you feel inclinded to ok.if you need more info im here ok.

mitch