So I recently came back from a trip up north, 500 miles each way. Just changed all the fluids, bike was cleaned and ready to go. Jumped on the scooter and did the superslab run north, running about 75 mph for about 10 hours.... When I got to where I was going it was raining. My bike ran good and strong the whole way. I stopped at my 1st destination and enjoyed myself... a few hours later it was time to venture to a different destination and I started my bike and it was rattling something fierce. The knock/metallic rattle was coming from the air cleaner side sounded like valve train but hard to pin down. Once the bike warmed up the sound died down quite a bit. I rode it anyway. The next day I rode it about 3/4 of the way home but the sound got progressively worse. So I asked my bro to pick me up with the trailer. The whole time the bike ran strong. No power problem. So off to the mechanic. So now heres the prognosis. Rear exhaust valve was stuck in the rear exhaust valve guide and had to be beat out with a hammer. Seemed to be hanging up. No other damage apparent, decided to go with new exhaust valves front and rear, new guide opened up a extra thousandth, new rings/hone/gaskets etc. Also new lifters... So has anyone else come across this? Mech said hasnt seen it but 2x in the twin cams, a few more times in the evo's.... I have never heard of it happening to anybody. Whats your take???