knocking

Yo peeps, Here's a wierd one - I had my 97 carb Blackbird on an angle (used a 2inch bit of wood under the center stand to lean it over). The idea being to check any leaks from a recent J-B weld repair of the collector box. So I started the bike with choke and no leaks :-) exhaust fumes normal...

Can anyone help me? My 2000 blackbird has 18000 miles. A couple of days ago I began to hearing a knocking noise coming from near the bottom and middle of my bike. It seems to repeat faster, the faster I go. When I'm not moving there is no noise. Also, I don't know if it's related but, I ran...