Before I take my 2002 520 EXC to a mechanic, I thought I'd check in here. While out riding yesterday, it suddenly started making a lot of noise from what seems to be the top end, but I'm not positive. Power seemed fine, just the noise, and it came on suddenly. I've checked the valves, and they are OK. I also checked the cam chain tensioner, and it has a few clicks left. So what next to check? Bike starts up and idles just fine. Just real noisy, and the noise coincides with RPMs. Pulling in the clutch has no effect on the noise. Odd part is that I adjusted the valves a few weeks ago, and afterwards, noticed the engine was noisy. So I rechecked, and the exhaust were way loose, so I corrected them, and the noise went away - until this last ride. Not sure if that has anything to do with anything. So what to check next? Or do I just take it in to the shop.