Got a chance to move from my 99 f4 to a 2000 blackbird but it has 80,000kms/ aprox 50 000 miles on it should I be concerned about this kind of mileage?

Psy

 

I shouldn't worry about that sort of mileage on a Honda or indeed any other Japanese motorcycle or car for that matter. The engineering is superb and the Blackbird is a great bike. Just make sure you change the oil and filter, air filter etc if you decide to buy it unless you know the full history of the bike and it's service history. I wish you all the best in your new purchase!