Hello out there. I just picked up my first ascot and I have a few questions for you engine guys. My bike had a knock in the motor that the PO was upfront about but he wasn't sure what was up. So when I got it home I took the head off and discovered a piece of metal sitting on top of the piston. I don't know where it came from because everything seems to be in tact. The valves didn't suffer but the head and piston both got a dinged up some. The piston is easy enough to source but the head I'm not so sure about. Anyway I guess my questions are, would it be possible to clean it up and run it? If not is a using a XL500 head as easy as changing out the exhaust studs? Also what years of the XL head are interchangeable? I'll try to figure out how to post pics in a bit. Thanks for any and all input.