GSXR knock

[-Savage-]

Hey all,

Noticed today a slight knock in the bike, seems like the top of the engine. Bike is a GSXR750 2005, 16000 miles, it was up at ~ 100 degrees. As I was in traffic I could hear the knock when at idle, and it would get faster with revs but at higher revs than idle you cant really hear it.

What is this likely to be?
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My Bikes - - - Royal Enfield 500 with sidecar, VFR800, CBR600FX,
Peugeot Speedfight 100, Kymco Hipster 125, GSXR750K5, Jawa TS 350

[Nope.]

Could be the valve clearances. Have you had them done at any time?
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Former: Derbi GP1 50, Sachs XTC 125, Suzuki GSXR 400 GK73A, Kawasaki ZX7R, Suzuki DR250, Yamaha RD350
Current: 2011 Yamaha XT660Z Ténéré, 2003 Yamaha YZR-R1 5PW (In Build), 2009 Kawasaki ZZR1400

[MaybeGuy]

[Nope.]