I just bought an 03 450exc from a great guy that changed the oil after every ride had valves adjusted and really kept the bike in wonderful condition. Went out today an put 15min in the bike and while riding in first gear to the truck it locked up. Won´t role forward or backward while in gear and can´t kick over. Help. Tell me this is a fluke. Tell me that this is a good bike so I can justify my leaving Blue.