hi. I've recently bought a cbr 1000 on an 06 plate with full dealer history and 3400 miles on the clock. The bike is mint EXCEPT for a knocking noise from the engine, only at up to 2000 rpm, and only when the engine is warmed up. The noise is pretty minor and i may just be being a bit paranoid, i was hoping somebody else may have had a similar experience and could advise whether it is normal or may have any thoughts on what the problem may be? Many thanks. Marc.