dropped a valve seat.....

[scooter1100]

Hey guys, I need some opinions on what to do ; At 40,000km ,I put a fresh set of rings, valve job and a cam in my 650L and got about 1500miles (2200km) on it before I got a valve clearance (Clacking) that was too big to adjust out. I did the rebuild because the cam and rockers wore on that same port last year. Upon removal of the head (sp.plug was loose?! btw) I found a seat had dropped about the thickness of a dime. Is there any point in trying using this head (if repairable), or should I get a new one, or even a rebuilt better than oem? Or anyone ever heard of locking the seats in mechanically? any suggestions appreciated

[frankstr]

Any good machine shop can put a oversize seat in ...no problem...