I just got a 99 Lc4 Enduro, has 12000 miles oil changed every 2500 miles and bearing replaced at 3,000 miles. This thing runs great! Valves Adjusted Every 4,000 Miles. I noticed today on the highway at 50 mile an hour shifted into 5th and rolled on the throttle and a clatter sounds like right side and maybe topend. It sounds like maybe timming chain? it stops once its not lugging or the RPMs plane out. This normal?