I'm new here so first off, Hello! I have a 1982 xj650. Bought it last year, it was my first bike. Learned how to ride fairly easy, and right at the end of the season it started spewing a gas/oil mixture from the shaft boot under the seat. This year I changed the oil, and fired it up. It rode up the street twice and then it died. I noticed that there's a whistle noise, so I'm guessing I have a head gasket leak that's allowing gas to get through and causing a loss in compression. I've never really worked on a bike so my question is, how hard is it to replace a head gasket on these?