Valve Issue?

[gzed]

Hi All,

I have a 2006 gz250 with 4500 miles that has a metallic tapping noise. I used a mechanic's stethoscope and it seems to be coming from the exhaust valves. I adjusted the valves to spec but the sound is unchanged.

Everything else about the bike is great, it has good acceleration, starts up fine, and has a solid idle. I have read through this forum trying other suggestions, even checked the cam chain tensioner. I thought it could be a loose cam chain slapping the engine wall, but no.

Is there anything else you guys can think of checking before I try to pull the head and take a peek inside? Thank you in advance!