I've got an 86 250R ATC, just recently the crank bearings were replaced as well as the rod, piston and rings. Now when I fire it up, I hear a grinding type of sound, almost like when you engage the kick starter when it is running. I have had this bike for a long time and I don't recall hearing a grinding noise like that ever before. It has been sitting about 10 mos. since blowing it up last Labor Day weekend. Any ideas? Thanks in advance.

JW