Last September I was riding back home to San Clemente, California on a 1990 Honda Transalp I had found on Craigslist in Rochester New York. My Clutch cable broke coming into South Dakota and I was waiting in Deadwood for the new one to arrive when I stumbled across a white 1970 R75/5 toaster with just over 32,000 miles on it and fell in love and purchased it. I joined the ABC and have used many of the fantastic Wobbly articles on carburetor and valve adjustment. After putting about 1500 miles on it since October, my wife and I decided to ride over the Ortega Hwy into Corona to watch a friend play his Sax with a reggae band.. We wanted to leave on time to make it back over the mountain before dark. While cruising down the 15 at about 70mph I felt through the footpads (and heard) a violent kuh thunk. I pulled in the clutch turned off the engine and coated to safety. I kicked it through with the ignition off a few times and it felt alright so I kick started it and heard an audible rattle rattle clank clank so I turned it off. AAA picked us up and brought is home. The next morning I pulled the valve covers and the valve were close to spec and the engine turned over easy with the spark plugs removed. I then pulled the pan and found no metal in the sump or oil pickup. I think the next step is to pull the transmission and inspect the flywheel and clutch to see what might have happened. Any help or clues to what might have happened would be greatly appreciated. I have a workshop manual. Today I will drain the transmission and look for metal. Thank you all out there in advance for any help. (I wish that I could have made the "Ralley in the alley tech day in San Diego!)