I have an 86 XT350, I had the motor rebuilt, and with that the timing chain was replaced, along with the valves. The problem I have is, the motor seems to have a top end rattle. It sounds like a timing chain, or valves to me, but I am reasured by my mechanic that all it tight and in adjustment. What else could be making this noise? Is it a common noise for these bikes? It seems to have all the power it should, and starts and runs fine.