Hey gang, I need the input of the Big Red Thumper experts. I know a guy who bought a used 1983 XL600 a few weeks back. It was in decent shape when he bought it. Well he took it out for an easy ride and about 20 miles into it, he heard a loud bang followed by a grinding noise. When he pulled in the clutch the engine died. He lost about 1/2 a litre of oil out of the Air filter box. He tried to kick it over. He got it to kick through with great difficulty and it sounded like a bucket of bolts. He thinks it is the piston. Anybody have any other ideas what the problem may be? Cost? How much would you pay to pick up this now "project bike"? Thanks.